Warning

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  • friendly_traceback,

  • friendly, and

  • friendly_idle.

The documentation does not reflect this change.

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Friendly tracebacks - in English

Friendly aims to provide friendlier feedback when an exception is raised than what is done by Python. Below, we can find some examples. SyntaxError cases, as well as TabError and IndentationError cases, are shown in a separate page. Not all cases handled by friendly are included here.

Note

The content of this page is generated by running trb_english.py located in the tests/ directory. This needs to be done explicitly, independently of updating the documentation using Sphinx.

Friendly version: 0.3.142 Python version: 3.7.8

ArithmeticError

Generic

Traceback (most recent call last):
  File "TESTS:\runtime\test_arithmetic_error.py", line 9, in test_Generic
    raise ArithmeticError('error')
ArithmeticError: error

`ArithmeticError` is the base class for those built-in exceptions
that are raised for various arithmetic errors.
It is unusual that you are seeing this exception;
normally, a more specific exception should have been raised.

Exception raised on line 9 of file TESTS:\runtime\test_arithmetic_error.py.

    7:         # Usually, a subclass such as ZeroDivisionError, etc., would
    8:         # likely be raised.
--> 9:         raise ArithmeticError('error')
   10:     except ArithmeticError as e:

        ArithmeticError:  <class ArithmeticError>

AssertionError

Generic

Traceback (most recent call last):
  File "TESTS:\runtime\test_assertion_error.py", line 8, in test_Generic
    raise AssertionError("Fake message")
AssertionError: Fake message

In Python, the keyword `assert` is used in statements of the form
`assert condition`, to confirm that `condition` is not `False`,
nor equivalent to `False` such as an empty list, etc.

If `condition` is `False` or equivalent, an `AssertionError` is raised.

Exception raised on line 8 of file TESTS:\runtime\test_assertion_error.py.

    6:         # We raise it explicitly, rather than with the keyword assert, since
    7:         # we don't want pytest to rewrite out test.
--> 8:         raise AssertionError("Fake message")
    9:     except AssertionError as e:

        AssertionError:  <class AssertionError>

AttributeError

Attribute from other module

Traceback (most recent call last):
  File "TESTS:\runtime\test_attribute_error.py", line 299, in test_Attribute_from_other_module
    keyword.pi
AttributeError: module 'keyword' has no attribute 'pi'

    Did you mean one of the following modules: `math, cmath`?
An `AttributeError` occurs when the code contains something like
    `object.x`
and `x` is not a method or attribute (variable) belonging to `object`.

Instead of the module `keyword`, perhaps you wanted to use
the attribute `pi` of one of the following modules:
`math, cmath`.

Exception raised on line 299 of file TESTS:\runtime\test_attribute_error.py.

   297:     import cmath
   298:     try:
-->299:         keyword.pi
   300:     except AttributeError as e:

        keyword:  <module keyword> from PYTHON_LIB:\keyword.py

Builtin function

Traceback (most recent call last):
  File "TESTS:\runtime\test_attribute_error.py", line 217, in test_Builtin_function
    len.text
AttributeError: 'builtin_function_or_method' object has no attribute 'text'

    Did you mean `len(text)`?

An `AttributeError` occurs when the code contains something like
    `object.x`
and `x` is not a method or attribute (variable) belonging to `object`.

`len` is a function. Perhaps you meant to write
`len(text)`

Exception raised on line 217 of file TESTS:\runtime\test_attribute_error.py.

   215:     text = 'Hello world!'
   216:     try:
-->217:         len.text
   218:     except AttributeError as e:

        text:  'Hello world!'
        len:  <builtin function len>

Builtin module with no file

Traceback (most recent call last):
  File "TESTS:\runtime\test_attribute_error.py", line 234, in test_Builtin_module_with_no_file
    sys.foo
AttributeError: module 'sys' has no attribute 'foo'

An `AttributeError` occurs when the code contains something like
    `object.x`
and `x` is not a method or attribute (variable) belonging to `object`.

Python tells us that no object with name `foo` is
found in module `sys`.

Exception raised on line 234 of file TESTS:\runtime\test_attribute_error.py.

   232:
   233:     try:
-->234:         sys.foo
   235:     except AttributeError as e:

        sys:  <module sys (builtin)>

Circular import

Traceback (most recent call last):
  File "TESTS:\runtime\test_attribute_error.py", line 329, in test_Circular_import
    import my_turtle1
  File "TESTS:\my_turtle1.py", line 4, in <module>
    a = my_turtle1.something
AttributeError: module 'my_turtle1' has no attribute 'something'

    Did you give your program the same name as a Python module?

An `AttributeError` occurs when the code contains something like
    `object.x`
and `x` is not a method or attribute (variable) belonging to `object`.

This should not happen:
Python tells us that module `my_turtle1` does not have an attribute named `something`.
However, it does not appear that module `my_turtle1` was imported.
I suspect that you used the name `my_turtle1.py` for your program
and that you also wanted to import a module with the same name
from Python's standard library.
If so, you should use a different name for your program.

Execution stopped on line 329 of file TESTS:\runtime\test_attribute_error.py.

   327:     stdlib_modules.names.append("my_turtle1")
   328:     try:
-->329:        import my_turtle1
   330:     except AttributeError as e:

Exception raised on line 4 of file TESTS:\my_turtle1.py.

   2: import my_turtle1
   3:
-->4: a = my_turtle1.something
          ^^^^^^^^^^^^^^^^^^^^

        my_turtle1:  <module my_turtle1> from TESTS:\my_turtle1.py

Circular import b

Traceback (most recent call last):
  File "TESTS:\runtime\test_attribute_error.py", line 346, in test_Circular_import_b
    import circular_c
  File "TESTS:\circular_c.py", line 4, in <module>
    a = circular_c.something
AttributeError: module 'circular_c' has no attribute 'something'

    You likely have a circular import.

An `AttributeError` occurs when the code contains something like
    `object.x`
and `x` is not a method or attribute (variable) belonging to `object`.

You likely have a circular import.
This can occur if, during the execution of the code in module `circular_c`
an attempt is made to import the same module again.

Execution stopped on line 346 of file TESTS:\runtime\test_attribute_error.py.

   344: def test_Circular_import_b():
   345:     try:
-->346:         import circular_c
   347:     except AttributeError as e:

Exception raised on line 4 of file TESTS:\circular_c.py.

   2: import circular_c
   3:
-->4: a = circular_c.something
          ^^^^^^^^^^^^^^^^^^^^

        circular_c:  <module circular_c> from TESTS:\circular_c.py

Generic

Traceback (most recent call last):
  File "TESTS:\runtime\test_attribute_error.py", line 24, in test_Generic
    A.x  # testing type
AttributeError: type object 'A' has no attribute 'x'

An `AttributeError` occurs when the code contains something like
    `object.x`
and `x` is not a method or attribute (variable) belonging to `object`.

The object `A` has no attribute named `x`.

Exception raised on line 24 of file TESTS:\runtime\test_attribute_error.py.

   22:
   23:     try:
-->24:         A.x  # testing type
   25:     except AttributeError as e:

        A:  <class A> from test_attribute_error.test_Generic

Generic different frame

Traceback (most recent call last):
  File "TESTS:\runtime\test_attribute_error.py", line 47, in test_Generic_different_frame
    a.attr
AttributeError: 'A' object has no attribute 'attr'

    Did you mean `attr2`?

An `AttributeError` occurs when the code contains something like
    `object.x`
and `x` is not a method or attribute (variable) belonging to `object`.

The object `a` has no attribute named `attr`.
Perhaps you meant to write `a.attr2` instead of `a.attr`

Exception raised on line 47 of file TESTS:\runtime\test_attribute_error.py.

   45:     a = f()
   46:     try:
-->47:         a.attr
   48:     except AttributeError as e:

        a:  <f.A object> from test_attribute_error.test_Generic_different_frame

Generic instance

Traceback (most recent call last):
  File "TESTS:\runtime\test_attribute_error.py", line 65, in test_Generic_instance
    a.x
AttributeError: 'A' object has no attribute 'x'

An `AttributeError` occurs when the code contains something like
    `object.x`
and `x` is not a method or attribute (variable) belonging to `object`.

The object `a` has no attribute named `x`.

Exception raised on line 65 of file TESTS:\runtime\test_attribute_error.py.

   63:     a = A()
   64:     try:
-->65:         a.x
   66:     except AttributeError as e:

        a:  <A object> from test_attribute_error.test_Generic_instance

Module attribute typo

Traceback (most recent call last):
  File "TESTS:\runtime\test_attribute_error.py", line 142, in test_Module_attribute_typo
    math.cost
AttributeError: module 'math' has no attribute 'cost'

    Did you mean `cos`?

An `AttributeError` occurs when the code contains something like
    `object.x`
and `x` is not a method or attribute (variable) belonging to `object`.

Instead of writing `math.cost`, perhaps you meant to write one of
the following names which are attributes of module `math`:
`cos, cosh, acos`

Exception raised on line 142 of file TESTS:\runtime\test_attribute_error.py.

   140:
   141:     try:
-->142:         math.cost
   143:     except AttributeError as e:

        math:  <module math (builtin)>

Nonetype

Traceback (most recent call last):
  File "TESTS:\runtime\test_attribute_error.py", line 181, in test_Nonetype
    a.b
AttributeError: 'NoneType' object has no attribute 'b'

An `AttributeError` occurs when the code contains something like
    `object.x`
and `x` is not a method or attribute (variable) belonging to `object`.

You are attempting to access the attribute `b`
for a variable whose value is `None`.
Exception raised on line 181 of file TESTS:\runtime\test_attribute_error.py.

   179:     a = None
   180:     try:
-->181:         a.b
   182:     except AttributeError as e:

        a:  None

Object attribute typo

Traceback (most recent call last):
  File "TESTS:\runtime\test_attribute_error.py", line 81, in test_Object_attribute_typo
    a.appendh(4)
AttributeError: 'list' object has no attribute 'appendh'

    Did you mean `append`?

An `AttributeError` occurs when the code contains something like
    `object.x`
and `x` is not a method or attribute (variable) belonging to `object`.

The object `a` has no attribute named `appendh`.
Perhaps you meant to write `a.append` instead of `a.appendh`

Exception raised on line 81 of file TESTS:\runtime\test_attribute_error.py.

   79:     try:
   80:         a = [1, 2, 3]
-->81:         a.appendh(4)
               ^^^^^^^^^
   82:     except AttributeError as e:

        a:  [1, 2, 3]

Perhaps comma

Traceback (most recent call last):
  File "TESTS:\runtime\test_attribute_error.py", line 200, in test_Perhaps_comma
    a = [abcd
AttributeError: 'str' object has no attribute 'defg'

    Did you mean to separate object names by a comma?

An `AttributeError` occurs when the code contains something like
    `object.x`
and `x` is not a method or attribute (variable) belonging to `object`.

`defg` is not an attribute of `abcd`.
However, both `abcd` and `defg` are known objects.
Perhaps you wrote a period to separate these two objects,
instead of using a comma.

Exception raised on line 200 of file TESTS:\runtime\test_attribute_error.py.

   198:     # fmt: off
   199:     try:
-->200:         a = [abcd
   201:         .defg]

        abcd:  'hello'
        defg:  'world'

Shadow stdlib module

Traceback (most recent call last):
  File "TESTS:\runtime\test_attribute_error.py", line 163, in test_Shadow_stdlib_module
    turtle.Pen
AttributeError: module 'turtle' has no attribute 'Pen'

    Did you give your program the same name as a Python module?

An `AttributeError` occurs when the code contains something like
    `object.x`
and `x` is not a method or attribute (variable) belonging to `object`.

You imported a module named `turtle` from `TESTS:\turtle.py`.
There is also a module named `turtle` in Python's standard library.
Perhaps you need to rename your module.

Exception raised on line 163 of file TESTS:\runtime\test_attribute_error.py.

   161:
   162:     try:
-->163:         turtle.Pen
   164:     except AttributeError as e:

        turtle:  <module turtle> from TESTS:\turtle.py

Tuple by accident

Traceback (most recent call last):
  File "TESTS:\runtime\test_attribute_error.py", line 269, in test_Tuple_by_accident
    something.upper()
AttributeError: 'tuple' object has no attribute 'upper'

    Did you write a comma by mistake?

An `AttributeError` occurs when the code contains something like
    `object.x`
and `x` is not a method or attribute (variable) belonging to `object`.

`something` is a tuple that contains a single item
which does have `'upper'` as an attribute.
Perhaps you added a trailing comma by mistake at the end of the line
where you defined `something`.

Exception raised on line 269 of file TESTS:\runtime\test_attribute_error.py.

   267:     something = "abc",  # note trailing comma
   268:     try:
-->269:         something.upper()
                ^^^^^^^^^^^^^^^
   270:     except AttributeError as e:

        something:  ('abc',)

Use builtin

Traceback (most recent call last):
  File "TESTS:\runtime\test_attribute_error.py", line 97, in test_Use_builtin
    a.length()
AttributeError: 'list' object has no attribute 'length'

    Did you mean `len(a)`?

An `AttributeError` occurs when the code contains something like
    `object.x`
and `x` is not a method or attribute (variable) belonging to `object`.

The object `a` has no attribute named `length`.
Perhaps you can use the Python builtin function `len` instead:
`len(a)`.
Exception raised on line 97 of file TESTS:\runtime\test_attribute_error.py.

   95:     try:
   96:         a = [1, 2, 3]
-->97:         a.length()
               ^^^^^^^^
   98:     except AttributeError as e:

        a:  [1, 2, 3]

Use join with str

Traceback (most recent call last):
  File "TESTS:\runtime\test_attribute_error.py", line 313, in test_Use_join_with_str
    a = ['a', '2'].join('abc') + ['b', '3'].join('\n')
AttributeError: 'list' object has no attribute 'join'

    Did you mean `'abc'.join(['a', '2'])`?

An `AttributeError` occurs when the code contains something like
    `object.x`
and `x` is not a method or attribute (variable) belonging to `object`.

The object `['a', '2']` has no attribute named `join`.
Perhaps you wanted something like `'abc'.join(['a', '2'])`.

Exception raised on line 313 of file TESTS:\runtime\test_attribute_error.py.

   311: def test_Use_join_with_str():
   312:     try:
-->313:         a = ['a', '2'].join('abc') + ['b', '3'].join('\n')
                    ^^^^^^^^^^^^^^^
   314:     except AttributeError as e:

Use synonym

Traceback (most recent call last):
  File "TESTS:\runtime\test_attribute_error.py", line 113, in test_Use_synonym
    a.add(4)
AttributeError: 'list' object has no attribute 'add'

    Did you mean `append`?

An `AttributeError` occurs when the code contains something like
    `object.x`
and `x` is not a method or attribute (variable) belonging to `object`.

The object `a` has no attribute named `add`.
However, `a` has the following attributes with similar meanings:
`append, extend, insert`.

Exception raised on line 113 of file TESTS:\runtime\test_attribute_error.py.

   111:     try:
   112:         a = [1, 2, 3]
-->113:         a.add(4)
                ^^^^^
   114:     except AttributeError as e:

        a:  [1, 2, 3]

Using slots

Traceback (most recent call last):
  File "TESTS:\runtime\test_attribute_error.py", line 254, in test_Using_slots
    f.b = 1
AttributeError: 'F' object has no attribute 'b'

An `AttributeError` occurs when the code contains something like
    `object.x`
and `x` is not a method or attribute (variable) belonging to `object`.

The object `f` has no attribute named `b`.
Note that object `f` uses `__slots__` which prevents
the creation of new attributes.
The following are some of its known attributes:
`a`.
Exception raised on line 254 of file TESTS:\runtime\test_attribute_error.py.

   252:     f = F()
   253:     try:
-->254:         f.b = 1
   255:     except AttributeError as e:

        f:  <F object> from test_attribute_error.test_Using_slots

FileNotFoundError

Generic

Traceback (most recent call last):
  File "TESTS:\runtime\test_file_not_found_error.py", line 6, in test_Generic
    open("does_not_exist")
FileNotFoundError: [Errno 2] No such file or directory: 'does_not_exist'

A `FileNotFoundError` exception indicates that you
are trying to open a file that cannot be found by Python.
This could be because you misspelled the name of the file.

In your program, the name of the
file that cannot be found is `does_not_exist`.

Exception raised on line 6 of file TESTS:\runtime\test_file_not_found_error.py.

   4: def test_Generic():
   5:     try:
-->6:         open("does_not_exist")
   7:     except FileNotFoundError as e:

        open:  <builtin function open>

ImportError

Circular import

Traceback (most recent call last):
  File "TESTS:\runtime\test_import_error.py", line 58, in test_Circular_import
    import circular_a
  File "TESTS:\circular_a.py", line 2, in <module>
    import circular_b
  File "TESTS:\circular_b.py", line 2, in <module>
    from circular_a import a
ImportError: cannot import name 'a' from 'circular_a' (C:\Users\andre\github\friendly-traceback\tests\circular_a.py)

    You have a circular import.

An `ImportError` exception indicates that a certain object could not
be imported from a module or package. Most often, this is
because the name of the object is not spelled correctly.

The object that could not be imported is `a`.
The module or package where it was
expected to be found is `circular_a`.

The problem was likely caused by what is known as a 'circular import'.
First, Python imported and started executing the code in file
   'TESTS:\runtime\test_import_error.py'.
which imports module `circular_a`.
During this process, the code in another file,
   'TESTS:\circular_b.py'
was executed. However in this last file, an attempt was made
to import the original module `circular_a`
a second time, before Python had completed the first import.

Execution stopped on line 58 of file TESTS:\runtime\test_import_error.py.

   56: def test_Circular_import():
   57:     try:
-->58:         import circular_a
   59:     except ImportError as e:

Exception raised on line 2 of file TESTS:\circular_b.py.

   1: """File used in for test_circular_import() in test_import_error.py"""
-->2: from circular_a import a

Simple import error

Traceback (most recent call last):
  File "TESTS:\runtime\test_import_error.py", line 44, in test_Simple_import_error
    from math import Pi
ImportError: cannot import name 'Pi' from 'math' (unknown location)

    Did you mean `pi`?

An `ImportError` exception indicates that a certain object could not
be imported from a module or package. Most often, this is
because the name of the object is not spelled correctly.

Perhaps you meant to import `pi` (from `math`) instead of `Pi`

Exception raised on line 44 of file TESTS:\runtime\test_import_error.py.

   42:
   43:     try:
-->44:         from math import Pi
   45:     except ImportError as e:

IndexError

Empty

Traceback (most recent call last):
  File "TESTS:\runtime\test_index_error.py", line 38, in test_Empty
    c = a[1]
IndexError: list index out of range

    `a` contains no item.

An `IndexError` occurs when you try to get an item from a list,
a tuple, or a similar object (sequence), and use an index which
does not exist; typically, this happens because the index you give
is greater than the length of the sequence.

You have tried to get the item with index `1` of `a`,
a `list` which contains no item.

Exception raised on line 38 of file TESTS:\runtime\test_index_error.py.

   36:     a = []
   37:     try:
-->38:         c = a[1]
                   ^^^^
   39:     except IndexError as e:

        a:  []

Long list

Traceback (most recent call last):
  File "TESTS:\runtime\test_index_error.py", line 24, in test_Long_list
    print(a[60], b[0])
IndexError: list index out of range

An `IndexError` occurs when you try to get an item from a list,
a tuple, or a similar object (sequence), and use an index which
does not exist; typically, this happens because the index you give
is greater than the length of the sequence.

You have tried to get the item with index `60` of `a`,
a `list` of length `40`.
The valid index values of `a` are integers ranging from
`-40` to `39`.

Exception raised on line 24 of file TESTS:\runtime\test_index_error.py.

   22:     b = tuple(range(50))
   23:     try:
-->24:         print(a[60], b[0])
                     ^^^^^
   25:     except IndexError as e:

        a:  [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, ...]
            len(a): 40

Short tuple

Traceback (most recent call last):
  File "TESTS:\runtime\test_index_error.py", line 8, in test_Short_tuple
    print(a[3], b[2])
IndexError: tuple index out of range

    Remember: the first item of a `tuple` is not at index 1 but at index 0.

An `IndexError` occurs when you try to get an item from a list,
a tuple, or a similar object (sequence), and use an index which
does not exist; typically, this happens because the index you give
is greater than the length of the sequence.

You have tried to get the item with index `3` of `a`,
a `tuple` of length `3`.
The valid index values of `a` are integers ranging from
`-3` to `2`.

Exception raised on line 8 of file TESTS:\runtime\test_index_error.py.

    6:     b = [1, 2, 3]
    7:     try:
--> 8:         print(a[3], b[2])
                     ^^^^
    9:     except IndexError as e:

        a:  (1, 2, 3)

KeyError

ChainMap

Traceback (most recent call last):
  File "PYTHON_LIB:\collections\__init__.py", line 984, in pop
    return self.maps[0].pop(key, *args)
KeyError: 42

    During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "TESTS:\runtime\test_key_error.py", line 62, in test_ChainMap
    d.pop(42)
  File "PYTHON_LIB:\collections\__init__.py", line 986, in pop
    raise KeyError('Key not found in the first mapping: {!r}'.format(key))
KeyError: 'Key not found in the first mapping: 42'

A `KeyError` is raised when a value is not found as a
key in a Python dict or in a similar object.

The key `42` cannot be found in `d`, an object of type `ChainMap`.

Execution stopped on line 62 of file TESTS:\runtime\test_key_error.py.

   60:     d = ChainMap({}, {})
   61:     try:
-->62:         d.pop(42)
   63:     except KeyError as e:

        d:  ChainMap({}, {})
        d.pop:  <bound method ChainMap.pop of ChainMap({}, {})>

Exception raised on line 986 of file PYTHON_LIB:\collections\__init__.py.

   984:             return self.maps[0].pop(key, *args)
   985:         except KeyError:
-->986:             raise KeyError('Key not found in the first mapping: {!r}'.format(key))

        key:  42
        KeyError:  <class KeyError>
        format:  <builtin function format>
        'Key not found in the first mapping: {!r}'.format:  <builtin method format of str object>

Forgot to convert to string

Traceback (most recent call last):
  File "TESTS:\runtime\test_key_error.py", line 115, in test_Forgot_to_convert_to_string
    print(squares[2])
KeyError: 2

    Did you forget to convert `2` into a string?

A `KeyError` is raised when a value is not found as a
key in a Python dict or in a similar object.

The key `2` cannot be found in the dict `squares`.
`squares` contains a string key which is identical to `str(2)`.
Perhaps you forgot to convert the key into a string.

Exception raised on line 115 of file TESTS:\runtime\test_key_error.py.

   113:     squares = {"1": 1, "2": 4, "3": 9}
   114:     try:
-->115:         print(squares[2])
                      ^^^^^^^^^^
   116:     except KeyError as e:

        squares:  {'1': 1, '2': 4, '3': 9}

Generic key error

Traceback (most recent call last):
  File "TESTS:\runtime\test_key_error.py", line 44, in test_Generic_key_error
    d["c"]
KeyError: 'c'

A `KeyError` is raised when a value is not found as a
key in a Python dict or in a similar object.

The key `'c'` cannot be found in the dict `d`.

Exception raised on line 44 of file TESTS:\runtime\test_key_error.py.

   42:     d = {"a": 1, "b": 2}
   43:     try:
-->44:         d["c"]
   45:     except KeyError as e:

        d:  {'a': 1, 'b': 2}

Popitem empty ChainMap

Traceback (most recent call last):
  File "PYTHON_LIB:\collections\__init__.py", line 977, in popitem
    return self.maps[0].popitem()
KeyError: 'popitem(): dictionary is empty'

    During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "TESTS:\runtime\test_key_error.py", line 26, in test_Popitem_empty_ChainMap
    alpha.popitem()
  File "PYTHON_LIB:\collections\__init__.py", line 979, in popitem
    raise KeyError('No keys found in the first mapping.')
KeyError: 'No keys found in the first mapping.'

    `alpha` is an empty `ChainMap`.

A `KeyError` is raised when a value is not found as a
key in a Python dict or in a similar object.

You tried to retrieve an item from `alpha` which is an empty `ChainMap`.

Execution stopped on line 26 of file TESTS:\runtime\test_key_error.py.

   24:     alpha = ChainMap({}, {})
   25:     try:
-->26:         alpha.popitem()
   27:     except KeyError as e:

        alpha:  ChainMap({}, {})
        alpha.popitem:  <bound method ChainMap.popitem of ChainMap({}, {})>

Exception raised on line 979 of file PYTHON_LIB:\collections\__init__.py.

   977:             return self.maps[0].popitem()
   978:         except KeyError:
-->979:             raise KeyError('No keys found in the first mapping.')

        KeyError:  <class KeyError>

Popitem empty dict

Traceback (most recent call last):
  File "TESTS:\runtime\test_key_error.py", line 8, in test_Popitem_empty_dict
    d.popitem()
KeyError: 'popitem(): dictionary is empty'

    `d` is an empty `dict`.

A `KeyError` is raised when a value is not found as a
key in a Python dict or in a similar object.

You tried to retrieve an item from `d` which is an empty `dict`.

Exception raised on line 8 of file TESTS:\runtime\test_key_error.py.

    6:     d = {}
    7:     try:
--> 8:         d.popitem()
    9:     except KeyError as e:

        d:  {}
        d.popitem:  <builtin method popitem of dict object>

Similar names

Traceback (most recent call last):
  File "TESTS:\runtime\test_key_error.py", line 145, in test_Similar_names
    a = second["alpha"]
KeyError: 'alpha'

    Did you mean `'alpha0'`?

A `KeyError` is raised when a value is not found as a
key in a Python dict or in a similar object.

The key `'alpha'` cannot be found in the dict `second`.
`second` has some keys similar to `'alpha'` including:
`'alpha0', 'alpha12', 'alpha11'`.

Exception raised on line 145 of file TESTS:\runtime\test_key_error.py.

   143:     second = {"alpha0": 1, "alpha11": 2, "alpha12": 3}
   144:     try:
-->145:         a = second["alpha"]
                    ^^^^^^^^^^^^^^^
   146:     except KeyError as e:

        second:  {'alpha0': 1, 'alpha11': 2, 'alpha12': 3}

String by mistake

Traceback (most recent call last):
  File "TESTS:\runtime\test_key_error.py", line 98, in test_String_by_mistake
    d["(0, 0)"]
KeyError: '(0, 0)'

    Did you convert `(0, 0)` into a string by mistake?

A `KeyError` is raised when a value is not found as a
key in a Python dict or in a similar object.

The key `'(0, 0)'` cannot be found in the dict `d`.
`'(0, 0)'` is a string.
There is a key of `d` whose string representation
is identical to `'(0, 0)'`.

Exception raised on line 98 of file TESTS:\runtime\test_key_error.py.

    96:     d = {(0, 0): "origin"}
    97:     try:
--> 98:         d["(0, 0)"]
    99:     except KeyError as e:

        d:  {(0, 0): 'origin'}

LookupError

Generic

Traceback (most recent call last):
  File "TESTS:\runtime\test_lookup_error.py", line 10, in test_Generic
    raise LookupError("Fake message")
LookupError: Fake message

`LookupError` is the base class for the exceptions that are raised
when a key or index used on a mapping or sequence is invalid.
It can also be raised directly by codecs.lookup().

Exception raised on line 10 of file TESTS:\runtime\test_lookup_error.py.

    8:         # other than possibly codecs.lookup(), which is why we raise
    9:         # it directly here for our example.
-->10:         raise LookupError("Fake message")
   11:     except LookupError as e:

        LookupError:  <class LookupError>

ModuleNotFoundError

Need to install module

Traceback (most recent call last):
  File "TESTS:\runtime\test_module_not_found_error.py", line 76, in test_Need_to_install_module
    import alphabet
ModuleNotFoundError: No module named 'alphabet'

A `ModuleNotFoundError` exception indicates that you
are trying to import a module that cannot be found by Python.
This could be because you misspelled the name of the module
or because it is not installed on your computer.

No module named `alphabet` can be imported.
Perhaps you need to install it.

Exception raised on line 76 of file TESTS:\runtime\test_module_not_found_error.py.

   74: def test_Need_to_install_module():
   75:     try:
-->76:         import alphabet
   77:     except ModuleNotFoundError as e:

Not a package

Traceback (most recent call last):
  File "TESTS:\runtime\test_module_not_found_error.py", line 22, in test_Not_a_package
    import os.xxx
ModuleNotFoundError: No module named 'os.xxx'; 'os' is not a package

A `ModuleNotFoundError` exception indicates that you
are trying to import a module that cannot be found by Python.
This could be because you misspelled the name of the module
or because it is not installed on your computer.

`xxx` cannot be imported from `os`.

Exception raised on line 22 of file TESTS:\runtime\test_module_not_found_error.py.

   20:
   21:     try:
-->22:         import os.xxx
   23:     except ModuleNotFoundError as e:

Not a package similar name

Traceback (most recent call last):
  File "TESTS:\runtime\test_module_not_found_error.py", line 36, in test_Not_a_package_similar_name
    import os.pathh
ModuleNotFoundError: No module named 'os.pathh'; 'os' is not a package

    Did you mean `import os.path`?

A `ModuleNotFoundError` exception indicates that you
are trying to import a module that cannot be found by Python.
This could be because you misspelled the name of the module
or because it is not installed on your computer.

Perhaps you meant `import os.path`.
`path` is a name similar to `pathh` and is a module that
can be imported from `os`.
Other objects with similar names that are part of
 `os` include `fspath`.

Exception raised on line 36 of file TESTS:\runtime\test_module_not_found_error.py.

   34: def test_Not_a_package_similar_name():
   35:     try:
-->36:         import os.pathh
   37:     except ModuleNotFoundError as e:

Object not module

Traceback (most recent call last):
  File "TESTS:\runtime\test_module_not_found_error.py", line 49, in test_Object_not_module
    import os.open
ModuleNotFoundError: No module named 'os.open'; 'os' is not a package

    Did you mean `from os import open`?

A `ModuleNotFoundError` exception indicates that you
are trying to import a module that cannot be found by Python.
This could be because you misspelled the name of the module
or because it is not installed on your computer.

`open` is not a separate module but an object that is part of `os`.

Exception raised on line 49 of file TESTS:\runtime\test_module_not_found_error.py.

   47: def test_Object_not_module():
   48:     try:
-->49:         import os.open
   50:     except ModuleNotFoundError as e:

        open:  <builtin function open>

Similar object not module

Traceback (most recent call last):
  File "TESTS:\runtime\test_module_not_found_error.py", line 62, in test_Similar_object_not_module
    import os.opend
ModuleNotFoundError: No module named 'os.opend'; 'os' is not a package

    Did you mean `from os import open`?

A `ModuleNotFoundError` exception indicates that you
are trying to import a module that cannot be found by Python.
This could be because you misspelled the name of the module
or because it is not installed on your computer.

Perhaps you meant `from os import open`.
`open` is a name similar to `opend` and is an object that
can be imported from `os`.
Other objects with similar names that are part of
 `os` include `popen, fdopen`.

Exception raised on line 62 of file TESTS:\runtime\test_module_not_found_error.py.

   60: def test_Similar_object_not_module():
   61:     try:
-->62:         import os.opend
   63:     except ModuleNotFoundError as e:

Standard library module

Traceback (most recent call last):
  File "TESTS:\runtime\test_module_not_found_error.py", line 7, in test_Standard_library_module
    import Tkinter
ModuleNotFoundError: No module named 'Tkinter'

    Did you mean `tkinter`?

A `ModuleNotFoundError` exception indicates that you
are trying to import a module that cannot be found by Python.
This could be because you misspelled the name of the module
or because it is not installed on your computer.

No module named `Tkinter` can be imported.
Perhaps you need to install it.
`tkinter` is an existing module that has a similar name.

Exception raised on line 7 of file TESTS:\runtime\test_module_not_found_error.py.

   5: def test_Standard_library_module():
   6:     try:
-->7:         import Tkinter
   8:     except ModuleNotFoundError as e:

no curses

Traceback (most recent call last):
  File "TESTS:\runtime\test_module_not_found_error.py", line 92, in test_no_curses
    import curses
  File "PYTHON_LIB:\curses\__init__.py", line 13, in <module>
    from _curses import *
ModuleNotFoundError: No module named '_curses'

    The curses module is rarely installed with Python on Windows.

A `ModuleNotFoundError` exception indicates that you
are trying to import a module that cannot be found by Python.
This could be because you misspelled the name of the module
or because it is not installed on your computer.

You have tried to import the curses module.
The curses module is rarely installed with Python on Windows.

Execution stopped on line 92 of file TESTS:\runtime\test_module_not_found_error.py.

   90:     def test_no_curses():
   91:         try:
-->92:             import curses
   93:         except ModuleNotFoundError as e:

Exception raised on line 13 of file PYTHON_LIB:\curses\__init__.py.

   11: """
   12:
-->13: from _curses import *
   14: import os as _os

NameError

Annotated variable

Traceback (most recent call last):
  File "TESTS:\runtime\test_name_error.py", line 24, in test_Annotated_variable
    y = x
NameError: name 'x' is not defined

    Did you use a colon instead of an equal sign?

A `NameError` exception indicates that a variable or
function name is not known to Python.
Most often, this is because there is a spelling mistake.
However, sometimes it is because the name is used
before being defined or given a value.

In your program, no object with the name `x` exists.
A type hint found for `x` in the global scope.
Perhaps you had used a colon instead of an equal sign and wrote

    x : 3

instead of

    x = 3

Exception raised on line 24 of file TESTS:\runtime\test_name_error.py.

   22: def test_Annotated_variable():
   23:     try:
-->24:         y = x
                   ^
   25:     except NameError as e:

Custom name

Traceback (most recent call last):
  File "TESTS:\runtime\test_name_error.py", line 163, in test_Custom_name
    python
NameError: name 'python' is not defined

    You are already using Python!
A `NameError` exception indicates that a variable or
function name is not known to Python.
Most often, this is because there is a spelling mistake.
However, sometimes it is because the name is used
before being defined or given a value.

You are already using Python!
Exception raised on line 163 of file TESTS:\runtime\test_name_error.py.

   161: def test_Custom_name():
   162:     try:
-->163:         python
                ^^^^^^
   164:     except NameError as e:

Free variable referenced

Traceback (most recent call last):
  File "TESTS:\runtime\test_name_error.py", line 149, in test_Free_variable_referenced
    outer()
  File "TESTS:\runtime\test_name_error.py", line 145, in outer
    inner()
  File "TESTS:\runtime\test_name_error.py", line 144, in inner
    return var
NameError: free variable 'var' referenced before assignment in enclosing scope

A `NameError` exception indicates that a variable or
function name is not known to Python.
Most often, this is because there is a spelling mistake.
However, sometimes it is because the name is used
before being defined or given a value.

In your program, `var` is an unknown name
that exists in an enclosing scope,
but has not yet been assigned a value.

Execution stopped on line 149 of file TESTS:\runtime\test_name_error.py.

   147:
   148:     try:
-->149:         outer()
   150:     except NameError as e:

        outer:  <function outer> from test_Free_variable_referenced

Exception raised on line 144 of file TESTS:\runtime\test_name_error.py.

   142:     def outer():
   143:         def inner():
-->144:             return var
                           ^^^
   145:         inner()

Generic

Traceback (most recent call last):
  File "TESTS:\runtime\test_name_error.py", line 9, in test_Generic
    this = something
NameError: name 'something' is not defined

A `NameError` exception indicates that a variable or
function name is not known to Python.
Most often, this is because there is a spelling mistake.
However, sometimes it is because the name is used
before being defined or given a value.

In your program, no object with the name `something` exists.
I have no additional information for you.

Exception raised on line 9 of file TESTS:\runtime\test_name_error.py.

    7: def test_Generic():
    8:     try:
--> 9:         this = something
                      ^^^^^^^^^
   10:     except NameError as e:

Missing import

Traceback (most recent call last):
  File "TESTS:\runtime\test_name_error.py", line 129, in test_Missing_import
    unicodedata.something
NameError: name 'unicodedata' is not defined

    Did you forget to import `unicodedata`?

A `NameError` exception indicates that a variable or
function name is not known to Python.
Most often, this is because there is a spelling mistake.
However, sometimes it is because the name is used
before being defined or given a value.

The name `unicodedata` is not defined in your program.
Perhaps you forgot to import `unicodedata` which is found
in Python's standard library.

Exception raised on line 129 of file TESTS:\runtime\test_name_error.py.

   127:
   128:     try:
-->129:         unicodedata.something
                ^^^^^^^^^^^
   130:     except NameError as e:

Synonym

Traceback (most recent call last):
  File "TESTS:\runtime\test_name_error.py", line 89, in test_Synonym
    cost  # wrote from math import * above
NameError: name 'cost' is not defined

    Did you mean `cos`?

A `NameError` exception indicates that a variable or
function name is not known to Python.
Most often, this is because there is a spelling mistake.
However, sometimes it is because the name is used
before being defined or given a value.

In your program, no object with the name `cost` exists.
Instead of writing `cost`, perhaps you meant one of the following:
*   Global scope: `cos`, `cosh`, `acos`

Exception raised on line 89 of file TESTS:\runtime\test_name_error.py.

   87:
   88:     try:
-->89:         cost  # wrote from math import * above
               ^^^^
   90:     except NameError as e:

OsError

Urllib error

Traceback (most recent call last):
  File "PYTHON_LIB:\urllib\request.py", line 1350, in do_open
       ... More lines not shown. ...
  File "PYTHON_LIB:\socket.py", line 707, in create_connection
    for res in getaddrinfo(host, port, 0, SOCK_STREAM):
  File "PYTHON_LIB:\socket.py", line 752, in getaddrinfo
    for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
socket.gaierror: [Errno 11001] getaddrinfo failed

    During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "TESTS:\runtime\test_os_error.py", line 7, in test_Urllib_error
    request.urlopen("http://does_not_exist")
       ... More lines not shown. ...
  File "PYTHON_LIB:\urllib\request.py", line 1378, in http_open
    return self.do_open(http.client.HTTPConnection, req)
  File "PYTHON_LIB:\urllib\request.py", line 1352, in do_open
    raise URLError(err)
URLError: <urlopen error [Errno 11001] getaddrinfo failed>

An exception of type `URLError` is a subclass of `OSError`.
An `OSError` exception is usually raised by the Operating System
to indicate that an operation is not allowed or that
a resource is not available.

I suspect that you are trying to connect to a server and
that a connection cannot be made.

If that is the case, check for typos in the URL
and check your internet connectivity.

Execution stopped on line 7 of file TESTS:\runtime\test_os_error.py.

   5:     from urllib import request, error
   6:     try:
-->7:         request.urlopen("http://does_not_exist")
   8:     except error.URLError as e:

        request:  <module urllib.request> from PYTHON_LIB:\urllib\request.py
        request.urlopen:  <function urlopen>

Exception raised on line 1352 of file PYTHON_LIB:\urllib\request.py.

   1350:                           encode_chunked=req.has_header('Transfer-encoding'))
   1351:             except OSError as err: # timeout error
-->1352:                 raise URLError(err)
   1353:             r = h.getresponse()

        global URLError:  <class urllib.error.URLError>

OverflowError

Generic

Traceback (most recent call last):
  File "TESTS:\runtime\test_overflow_error.py", line 6, in test_Generic
    2.0 ** 1600
OverflowError: (34, 'Result too large')

An `OverflowError` is raised when the result of an arithmetic operation
is too large to be handled by the computer's processor.

Exception raised on line 6 of file TESTS:\runtime\test_overflow_error.py.

   4: def test_Generic():
   5:     try:
-->6:         2.0 ** 1600
   7:     except OverflowError as e:

RecursionError

Generic

Traceback (most recent call last):
  File "TESTS:\runtime\test_recursion_error.py", line 8, in test_Generic
    a()
       ... More lines not shown. ...
  File "TESTS:\runtime\test_recursion_error.py", line 6, in a
    return a()
  File "TESTS:\runtime\test_recursion_error.py", line 6, in a
    return a()
RecursionError: maximum recursion depth exceeded

A `RecursionError` is raised when a function calls itself,
directly or indirectly, too many times.
It almost always indicates that you made an error in your code
and that your program would never stop.

Execution stopped on line 8 of file TESTS:\runtime\test_recursion_error.py.

    6:         return a()
    7:     try:
--> 8:         a()
    9:     except RecursionError as e:

        a:  <function a> from test_Generic

Exception raised on line 6 of file TESTS:\runtime\test_recursion_error.py.

   4: def test_Generic():
   5:     def a():
-->6:         return a()
                     ^^^
   7:     try:

        a:  <function a> from test_Generic

TypeError

Bad type for unary operator

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 371, in test_Bad_type_for_unary_operator
    a =+ "def"
TypeError: bad operand type for unary +: 'str'

    Perhaps you meant to write `+=` instead of `=+`
A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

You tried to use the unary operator '+'
with the following type of object: a string (`str`).
This operation is not defined for this type of object.

Perhaps you meant to write `+=` instead of `=+`

Exception raised on line 371 of file TESTS:\runtime\test_type_error.py.

   369:         # fmt: off
   370:         a = "abc"
-->371:         a =+ "def"
                   ^^^^^^^
   372:         # fmt: on

Builtin has no len

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 780, in test_Builtin_has_no_len
    len("Hello world".split)
TypeError: object of type 'builtin_function_or_method' has no len()

    Did you forget to call `"Hello world".split`?

A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

I suspect that you forgot to add parentheses to call `"Hello world".split`.
You might have meant to write:
`len("Hello world".split())`

Exception raised on line 780 of file TESTS:\runtime\test_type_error.py.

   778: def test_Builtin_has_no_len():
   779:     try:
-->780:         len("Hello world".split)
   781:     except TypeError as e:

        len:  <builtin function len>
        "Hello world".split:  <builtin method split of str object>

Can only concatenate

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 37, in test_Can_only_concatenate
    result = a_tuple + a_list
TypeError: can only concatenate tuple (not "list") to tuple

A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

You tried to concatenate (add) two different types of objects:
a `tuple` and a `list`.

Exception raised on line 37 of file TESTS:\runtime\test_type_error.py.

   35:         a_tuple = (1, 2, 3)
   36:         a_list = [1, 2, 3]
-->37:         result = a_tuple + a_list
                        ^^^^^^^^^^^^^^^^
   38:     except TypeError as e:

        a_list:  [1, 2, 3]
        a_tuple:  (1, 2, 3)

Cannot convert dictionary update sequence

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 766, in test_Cannot_convert_dictionary_update_sequence
    dd.update([1, 2, 3])
TypeError: cannot convert dictionary update sequence element #0 to a sequence

    Perhaps you need to use the `dict.fromkeys()` method.

A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

`dict.update()` does not accept a sequence as an argument.
Instead of writing `dd.update([1, 2, 3])`
perhaps you should use the `dict.fromkeys()` method: `dd.update( dict.fromkeys([1, 2, 3]) )`.

Exception raised on line 766 of file TESTS:\runtime\test_type_error.py.

   764:     dd = {"a": "a"}
   765:     try:
-->766:         dd.update([1, 2, 3])
   767:     except TypeError as e:

        dd:  {'a': 'a'}
        dd.update:  <builtin method update of dict object>

Cannot multiply by non int

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 570, in test_Cannot_multiply_by_non_int
    "a" * "2"
TypeError: can't multiply sequence by non-int of type 'str'

    Did you forget to convert `"2"` into an integer?

A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

You can only multiply sequences, such as list, tuples,
 strings, etc., by integers.
Perhaps you forgot to convert `"2"` into an integer.

Exception raised on line 570 of file TESTS:\runtime\test_type_error.py.

   568:
   569:     try:
-->570:         "a" * "2"
   571:     except TypeError as e:

Cannot unpack non iterable object

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 738, in test_Cannot_unpack_non_iterable_object
    a, b = 42.0
TypeError: cannot unpack non-iterable float object

A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

Unpacking is a convenient way to assign a name,
to each item of an iterable.
An iterable is an object capable of returning its members one at a time.
Python containers (`list, tuple, dict`, etc.) are iterables,
but not objects of type `float`.

Exception raised on line 738 of file TESTS:\runtime\test_type_error.py.

   736: def test_Cannot_unpack_non_iterable_object():
   737:     try:
-->738:         a, b = 42.0
   739:     except TypeError as e:

Comparison not supported

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 320, in test_Comparison_not_supported
    b >= a
TypeError: '>=' not supported between instances of 'int' and 'str'

    Did you forget to convert the string `a` into an integer (`int`)?

A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

You tried to do an order comparison (>=)
between two incompatible types of objects:
an integer (`int`) and a string (`str`).
Perhaps you forgot to convert the string `a` into an integer (`int`).

Exception raised on line 320 of file TESTS:\runtime\test_type_error.py.

   318:         a = "2"
   319:         b = 42
-->320:         b >= a
   321:     except TypeError as e:

        a:  '2'
        b:  42

Derive from BaseException

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 513, in test_Derive_from_BaseException
    raise "exception"  # noqa
TypeError: exceptions must derive from BaseException

A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

In Python 3, exceptions must be derived from BaseException.

Exception raised on line 513 of file TESTS:\runtime\test_type_error.py.

   511: def test_Derive_from_BaseException():
   512:     try:
-->513:         raise "exception"  # noqa
   514:     except TypeError as e:

Indices must be integers or slices

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 652, in test_Indices_must_be_integers_or_slices
    [1, 2, 3]["2"]
TypeError: list indices must be integers or slices, not str

    Did you forget to convert `"2"` into an integer?

A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

In the expression `[1, 2, 3]["2"]`
what is included between the square brackets, `[...]`,
must be either an integer or a slice
(`start:stop` or `start:stop:step`)
and you have used a string (`str`) instead.

Perhaps you forgot to convert `"2"` into an integer.

Exception raised on line 652 of file TESTS:\runtime\test_type_error.py.

   650:
   651:     try:
-->652:         [1, 2, 3]["2"]
   653:     except TypeError as e:

Not an integer

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 615, in test_Not_an_integer
    range(c, d)
TypeError: 'str' object cannot be interpreted as an integer

    Did you forget to convert `c, d` into integers?

A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

You wrote an object of type `str` where an integer was expected.
Perhaps you forgot to convert `c, d` into integers.
Exception raised on line 615 of file TESTS:\runtime\test_type_error.py.

   613:     c, d = "2", "3"
   614:     try:
-->615:         range(c, d)
   616:     except TypeError as e:

        c:  '2'
        d:  '3'
        range:  <class range>

Not callable

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 500, in test_Not_callable
    _ = [1, 2](a + b)
TypeError: 'list' object is not callable

    Did you mean `[1, 2][a + b]`?

A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

Because of the surrounding parenthesis, `(a + b)`
is interpreted by Python as indicating a function call for
`[1, 2]`, which is an object of type `list`
which cannot be called.

However, `[1, 2]` is a sequence.
Perhaps you meant to use `[]` instead of `()` and write
`[1, 2][a + b]`

Exception raised on line 500 of file TESTS:\runtime\test_type_error.py.

   498:     try:
   499:         a, b = 3, 7
-->500:         _ = [1, 2](a + b)
                    ^^^^^^^^^^^^^
   501:     except TypeError as e:

        a:  3
        b:  7
        a + b:  10

Object is not iterable

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 724, in test_Object_is_not_iterable
    list(42)
TypeError: 'int' object is not iterable

A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

An iterable is an object capable of returning its members one at a time.
Python containers (`list, tuple, dict`, etc.) are iterables.
An iterable is required here.

Exception raised on line 724 of file TESTS:\runtime\test_type_error.py.

   722: def test_Object_is_not_iterable():
   723:     try:
-->724:         list(42)
   725:     except TypeError as e:

        list:  <class list>

Object is not subscriptable

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 710, in test_Object_is_not_subscriptable
    a = f[1]
TypeError: 'function' object is not subscriptable

    Did you mean `f(1)`?

A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

Subscriptable objects are typically containers from which
you can retrieve item using the notation `[...]`.

Perhaps you meant to write `f(1)`.

Exception raised on line 710 of file TESTS:\runtime\test_type_error.py.

   708:
   709:     try:
-->710:         a = f[1]
                    ^^^^
   711:     except TypeError as e:

        f:  <function f> from test_Object_is_not_subscriptable

Slice indices must be integers or None

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 666, in test_Slice_indices_must_be_integers_or_None
    [1, 2, 3][1.0:2.0]
TypeError: slice indices must be integers or None or have an __index__ method

A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

When using a slice to extract a range of elements
from a sequence, that is something like
`[start:stop]` or `[start:stop:step]`
each of `start`, `stop`, `step` must be either an integer, `None`,
or possibly some other object having an `__index__` method.

Exception raised on line 666 of file TESTS:\runtime\test_type_error.py.

   664: def test_Slice_indices_must_be_integers_or_None():
   665:     try:
-->666:         [1, 2, 3][1.0:2.0]
   667:     except TypeError as e:

Too few positional argument

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 441, in test_Too_few_positional_argument
    fn(1)
TypeError: fn() missing 2 required positional arguments: 'b' and 'c'

A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

You apparently have called the function 'fn()' with
fewer positional arguments than it requires (2 missing).

Exception raised on line 441 of file TESTS:\runtime\test_type_error.py.

   439:
   440:     try:
-->441:         fn(1)
   442:     except TypeError as e:

        fn:  <function fn> from test_Too_few_positional_argument

Too many positional argument

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 422, in test_Too_many_positional_argument
    A().f(1)
TypeError: f() takes 1 positional argument but 2 were given

    Perhaps you forgot `self` when defining `f`.

A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

You apparently have called the function `f` with
2 positional argument(s) while it requires 1
such positional argument(s).
Perhaps you forgot `self` when defining `f`.

Exception raised on line 422 of file TESTS:\runtime\test_type_error.py.

   420:
   421:     try:
-->422:         A().f(1)
   423:     except TypeError as e:

        A:  <class A> from test_type_error.test_Too_many_positional_argument

Tuple no item assignment

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 389, in test_Tuple_no_item_assignment
    a[0] = 0
TypeError: 'tuple' object does not support item assignment

    Did you mean to use a list?

A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

In Python, some objects are known as immutable:
once defined, their value cannot be changed.
You tried change part of such an immutable object: a `tuple`,
most likely by using an indexing operation.
Perhaps you meant to use a list instead.

Exception raised on line 389 of file TESTS:\runtime\test_type_error.py.

   387:     a = (1, 2, 3)
   388:     try:
-->389:         a[0] = 0
   390:     except TypeError as e:

        a:  (1, 2, 3)
        a[0]:  1

Unhachable type

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 683, in test_Unhachable_type
    {[1, 2]: 1}
TypeError: unhashable type: 'list'

A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

Only hashable objects can be used
as elements of `set` or keys of `dict`.
Hashable objects are objects that do not change value
once they have been created.Instead of using a `list`, consider using a `tuple`.

Exception raised on line 683 of file TESTS:\runtime\test_type_error.py.

   681: def test_Unhachable_type():
   682:     try:
-->683:         {[1, 2]: 1}
   684:     except TypeError as e:

Unsupported operand types

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 283, in test_Unsupported_operand_types
    a @= b
TypeError: unsupported operand type(s) for @=: 'str' and 'int'

A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

You tried to use the operator @=
using two incompatible types of objects:
a string (`str`) and an integer (`int`).
This operator is normally used only
for multiplication of matrices.

Exception raised on line 283 of file TESTS:\runtime\test_type_error.py.

   281:         a = "a"
   282:         b = 2
-->283:         a @= b
   284:     except TypeError as e:

        a:  'a'
        b:  2

function has no len

Traceback (most recent call last):
  File "TESTS:\runtime\test_type_error.py", line 796, in test_function_has_no_len
    len(bad)
TypeError: object of type 'function' has no len()

    Did you forget to call `bad`?

A `TypeError` is usually caused by trying
to combine two incompatible types of objects,
by calling a function with the wrong type of object,
or by trying to do an operation not allowed on a given type of object.

I suspect that you forgot to add parentheses to call `bad`.
You might have meant to write:
`len(bad())`

Exception raised on line 796 of file TESTS:\runtime\test_type_error.py.

   794:         pass
   795:     try:
-->796:         len(bad)
   797:     except TypeError as e:

        bad:  <function bad> from test_function_has_no_len
        len:  <builtin function len>

UnboundLocalError

Missing both

Traceback (most recent call last):
  File "TESTS:\runtime\test_unbound_local_error.py", line 61, in test_Missing_both
    outer_missing_both()
  File "TESTS:\runtime\test_unbound_local_error.py", line 22, in outer_missing_both
    inner()
  File "TESTS:\runtime\test_unbound_local_error.py", line 21, in inner
    spam_missing_both += 1
UnboundLocalError: local variable 'spam_missing_both' referenced before assignment

    Did you forget to add either `global spam_missing_both` or
    `nonlocal spam_missing_both`?

In Python, variables that are used inside a function are known as
local variables. Before they are used, they must be assigned a value.
A variable that is used before it is assigned a value is assumed to
be defined outside that function; it is known as a `global`
(or sometimes `nonlocal`) variable. You cannot assign a value to such
a global variable inside a function without first indicating to
Python that this is a global variable, otherwise you will see
an `UnboundLocalError`.

The name `spam_missing_both` exists in both the global and nonlocal scope.
This can be rather confusing and is not recommended.
Depending on which variable you wanted to refer to, you needed to add either

    global spam_missing_both

or

    nonlocal spam_missing_both

as the first line inside your function.

Execution stopped on line 61 of file TESTS:\runtime\test_unbound_local_error.py.

   59: def test_Missing_both():
   60:     try:
-->61:         outer_missing_both()
   62:     except UnboundLocalError as e:

        global outer_missing_both:  <function outer_missing_both>

Exception raised on line 21 of file TESTS:\runtime\test_unbound_local_error.py.

   19:     spam_missing_both = 2
   20:     def inner():
-->21:         spam_missing_both += 1
   22:     inner()

        global spam_missing_both:  1

Missing global

Traceback (most recent call last):
  File "TESTS:\runtime\test_unbound_local_error.py", line 27, in test_Missing_global
    outer_missing_global()
  File "TESTS:\runtime\test_unbound_local_error.py", line 10, in outer_missing_global
    inner()
  File "TESTS:\runtime\test_unbound_local_error.py", line 9, in inner
    spam_missing_global += 1
UnboundLocalError: local variable 'spam_missing_global' referenced before assignment

    Did you forget to add `global spam_missing_global`?

In Python, variables that are used inside a function are known as
local variables. Before they are used, they must be assigned a value.
A variable that is used before it is assigned a value is assumed to
be defined outside that function; it is known as a `global`
(or sometimes `nonlocal`) variable. You cannot assign a value to such
a global variable inside a function without first indicating to
Python that this is a global variable, otherwise you will see
an `UnboundLocalError`.

The name `spam_missing_global` exists in the global scope.
Perhaps the statement

    global spam_missing_global

should have been included as the first line inside your function.

Execution stopped on line 27 of file TESTS:\runtime\test_unbound_local_error.py.

   25: def test_Missing_global():
   26:     try:
-->27:         outer_missing_global()
   28:     except UnboundLocalError as e:

        global outer_missing_global:  <function outer_missing_global>

Exception raised on line 9 of file TESTS:\runtime\test_unbound_local_error.py.

    7: def outer_missing_global():
    8:     def inner():
--> 9:         spam_missing_global += 1
   10:     inner()

        global spam_missing_global:  1

Missing nonlocal

Traceback (most recent call last):
  File "TESTS:\runtime\test_unbound_local_error.py", line 44, in test_Missing_nonlocal
    outer_missing_nonlocal()
  File "TESTS:\runtime\test_unbound_local_error.py", line 16, in outer_missing_nonlocal
    inner()
  File "TESTS:\runtime\test_unbound_local_error.py", line 15, in inner
    spam_missing_nonlocal += 1
UnboundLocalError: local variable 'spam_missing_nonlocal' referenced before assignment

    Did you forget to add `nonlocal spam_missing_nonlocal`?

In Python, variables that are used inside a function are known as
local variables. Before they are used, they must be assigned a value.
A variable that is used before it is assigned a value is assumed to
be defined outside that function; it is known as a `global`
(or sometimes `nonlocal`) variable. You cannot assign a value to such
a global variable inside a function without first indicating to
Python that this is a global variable, otherwise you will see
an `UnboundLocalError`.

The name `spam_missing_nonlocal` exists in the nonlocal scope.
Perhaps the statement

    nonlocal spam_missing_nonlocal

should have been included as the first line inside your function.

Execution stopped on line 44 of file TESTS:\runtime\test_unbound_local_error.py.

   42: def test_Missing_nonlocal():
   43:     try:
-->44:         outer_missing_nonlocal()
   45:     except UnboundLocalError as e:

        global outer_missing_nonlocal:  <function outer_missing_nonlocal>

Exception raised on line 15 of file TESTS:\runtime\test_unbound_local_error.py.

   13:     spam_missing_nonlocal = 1
   14:     def inner():
-->15:         spam_missing_nonlocal += 1
   16:     inner()

Typo in local

Traceback (most recent call last):
  File "TESTS:\runtime\test_unbound_local_error.py", line 97, in test_Typo_in_local
    test2()
  File "TESTS:\runtime\test_unbound_local_error.py", line 94, in test2
    alpha3 += 1
UnboundLocalError: local variable 'alpha3' referenced before assignment

    Did you mean `alpha2`?

In Python, variables that are used inside a function are known as
local variables. Before they are used, they must be assigned a value.
A variable that is used before it is assigned a value is assumed to
be defined outside that function; it is known as a `global`
(or sometimes `nonlocal`) variable. You cannot assign a value to such
a global variable inside a function without first indicating to
Python that this is a global variable, otherwise you will see
an `UnboundLocalError`.

Instead of writing `alpha3`, perhaps you meant one of the following:
*   Local scope: `alpha2`, `alpha1`

Execution stopped on line 97 of file TESTS:\runtime\test_unbound_local_error.py.

   95:
   96:     try:
-->97:         test2()
   98:     except UnboundLocalError as e:

        test2:  <function test2> from test_Typo_in_local

Exception raised on line 94 of file TESTS:\runtime\test_unbound_local_error.py.

   92:         alpha1 = 1
   93:         alpha2 = 1
-->94:         alpha3 += 1

UnknownError

Generic

Traceback (most recent call last):
  File "TESTS:\runtime\test_unknown_error.py", line 12, in test_Generic
    raise MyException("Some informative message about an unknown exception.")
MyException: Some informative message about an unknown exception.

No information is known about this exception.
Please report this example to https://github.com/aroberge/friendly/issues.
If you are using a REPL, use `www('bug')` to do so.

If you are using the Friendly console, use `www()` to
do an Internet search for this particular case.

Exception raised on line 12 of file TESTS:\runtime\test_unknown_error.py.

   10:     friendly_traceback.debug_helper.DEBUG = False
   11:     try:
-->12:         raise MyException("Some informative message about an unknown exception.")
   13:     except Exception as e:

        global MyException:  <class test_unknown_error.MyException>

ValueError

Date invalid month

Traceback (most recent call last):
  File "TESTS:\runtime\test_value_error.py", line 58, in test_Date_invalid_month
    d = date(2021, 13, 1)
ValueError: month must be in 1..12

    Did you specify an invalid month?

A `ValueError` indicates that a function or an operation
received an argument of the right type, but an inappropriate value.

I am guessing that you specify an invalid value for a month
in a `date` object. Valid values are integers, from 1 to 12.

Exception raised on line 58 of file TESTS:\runtime\test_value_error.py.

   56:     from datetime import date
   57:     try:
-->58:         d = date(2021, 13, 1)
                   ^^^^^^^^^^^^^^^^^
   59:     except ValueError as e:

        date:  <class datetime.date>

Not enough values to unpack

Traceback (most recent call last):
  File "TESTS:\runtime\test_value_error.py", line 28, in test_Not_enough_values_to_unpack
    a, b, c = d
ValueError: not enough values to unpack (expected 3, got 2)

A `ValueError` indicates that a function or an operation
received an argument of the right type, but an inappropriate value.

Unpacking is a convenient way to assign a name,
to each item of an iterable.
In this instance, there are more names (3)
than the length of the iterable, a string (`str`) of length 2.

Exception raised on line 28 of file TESTS:\runtime\test_value_error.py.

   26:     d = "ab"
   27:     try:
-->28:         a, b, c = d
   29:     except ValueError as e:

        d:  'ab'

Too many values to unpack

Traceback (most recent call last):
  File "TESTS:\runtime\test_value_error.py", line 43, in test_Too_many_values_to_unpack
    a, b = c
ValueError: too many values to unpack (expected 2)

A `ValueError` indicates that a function or an operation
received an argument of the right type, but an inappropriate value.

Unpacking is a convenient way to assign a name,
to each item of an iterable.
In this instance, there are fewer names (2)
than the length of the iterable, a `list` of length 3.

Exception raised on line 43 of file TESTS:\runtime\test_value_error.py.

   41:     c = [1, 2, 3]
   42:     try:
-->43:         a, b = c
   44:     except ValueError as e:

        c:  [1, 2, 3]

ZeroDivisionError

Complex division

Traceback (most recent call last):
  File "TESTS:\runtime\test_zero_division_error.py", line 155, in test_Complex_division
    1 / zero
ZeroDivisionError: complex division by zero

A `ZeroDivisionError` occurs when you are attempting to divide a value
by zero either directly or by using some other mathematical operation.

You are dividing by the following term

     zero

which is equal to zero.

Exception raised on line 155 of file TESTS:\runtime\test_zero_division_error.py.

   153:     zero = 0j
   154:     try:
-->155:         1 / zero
   156:     except ZeroDivisionError as e:

        zero:  0j

Division by zero literal

Traceback (most recent call last):
  File "TESTS:\runtime\test_zero_division_error.py", line 199, in test_Division_by_zero_literal
    1. / 0
ZeroDivisionError: float division by zero

A `ZeroDivisionError` occurs when you are attempting to divide a value
by zero either directly or by using some other mathematical operation.

You are dividing by zero.

Exception raised on line 199 of file TESTS:\runtime\test_zero_division_error.py.

   197:
   198:     try:
-->199:         1. / 0
   200:     except ZeroDivisionError as e:

Division operator

Traceback (most recent call last):
  File "TESTS:\runtime\test_zero_division_error.py", line 17, in test_Division_operator
    1 / zero
ZeroDivisionError: division by zero

A `ZeroDivisionError` occurs when you are attempting to divide a value
by zero either directly or by using some other mathematical operation.

You are dividing by the following term

     zero

which is equal to zero.

Exception raised on line 17 of file TESTS:\runtime\test_zero_division_error.py.

   15:
   16:     try:
-->17:         1 / zero
   18:     except ZeroDivisionError as e:

        zero:  0

Divmod

Traceback (most recent call last):
  File "TESTS:\runtime\test_zero_division_error.py", line 82, in test_Divmod
    divmod(1, zero)
ZeroDivisionError: integer division or modulo by zero

A `ZeroDivisionError` occurs when you are attempting to divide a value
by zero either directly or by using some other mathematical operation.

The second argument of the `divmod()` function is zero.

Exception raised on line 82 of file TESTS:\runtime\test_zero_division_error.py.

   80:     zero = 0
   81:     try:
-->82:         divmod(1, zero)
   83:     except ZeroDivisionError as e:

        zero:  0
        divmod:  <builtin function divmod>

Float division

Traceback (most recent call last):
  File "TESTS:\runtime\test_zero_division_error.py", line 125, in test_Float_division
    1 / zero
ZeroDivisionError: float division by zero

A `ZeroDivisionError` occurs when you are attempting to divide a value
by zero either directly or by using some other mathematical operation.

You are dividing by the following term

     zero

which is equal to zero.

Exception raised on line 125 of file TESTS:\runtime\test_zero_division_error.py.

   123:     zero = 0.
   124:     try:
-->125:         1 / zero
   126:     except ZeroDivisionError as e:

        zero:  0.0

Float divmod

Traceback (most recent call last):
  File "TESTS:\runtime\test_zero_division_error.py", line 140, in test_Float_divmod
    divmod(1, zero)
ZeroDivisionError: float divmod()

A `ZeroDivisionError` occurs when you are attempting to divide a value
by zero either directly or by using some other mathematical operation.

The second argument of the `divmod()` function is equal to zero.

Exception raised on line 140 of file TESTS:\runtime\test_zero_division_error.py.

   138:     zero = 0.
   139:     try:
-->140:         divmod(1, zero)
   141:     except ZeroDivisionError as e:

        zero:  0.0
        divmod:  <builtin function divmod>

Float modulo

Traceback (most recent call last):
  File "TESTS:\runtime\test_zero_division_error.py", line 110, in test_Float_modulo
    1 % zero
ZeroDivisionError: float modulo

A `ZeroDivisionError` occurs when you are attempting to divide a value
by zero either directly or by using some other mathematical operation.

Using the modulo operator, you are dividing by the following term

     zero

which is equal to zero.

Exception raised on line 110 of file TESTS:\runtime\test_zero_division_error.py.

   108:
   109:     try:
-->110:         1 % zero
   111:     except ZeroDivisionError as e:

        zero:  0.0

Integer division operator

Traceback (most recent call last):
  File "TESTS:\runtime\test_zero_division_error.py", line 42, in test_Integer_division_operator
    1 // zero
ZeroDivisionError: integer division or modulo by zero

A `ZeroDivisionError` occurs when you are attempting to divide a value
by zero either directly or by using some other mathematical operation.

You are dividing by the following term

     zero

which is equal to zero.

Exception raised on line 42 of file TESTS:\runtime\test_zero_division_error.py.

   40:
   41:     try:
-->42:         1 // zero
   43:     except ZeroDivisionError as e:

        zero:  0

Mixed operations

Traceback (most recent call last):
  File "TESTS:\runtime\test_zero_division_error.py", line 212, in test_Mixed_operations
    a = divmod(8, 1 // 2)
ZeroDivisionError: integer division or modulo by zero

A `ZeroDivisionError` occurs when you are attempting to divide a value
by zero either directly or by using some other mathematical operation.

The following mathematical expression includes a division by zero:

    divmod(8, 1 // 2)

Exception raised on line 212 of file TESTS:\runtime\test_zero_division_error.py.

   210: def test_Mixed_operations():
   211:     try:
-->212:         a = divmod(8, 1 // 2)
                    ^^^^^^^^^^^^^^^^^
   213:     except ZeroDivisionError as e:

        divmod:  <builtin function divmod>
        1 // 2:  0

Modulo operator

Traceback (most recent call last):
  File "TESTS:\runtime\test_zero_division_error.py", line 67, in test_Modulo_operator
    1 % zero
ZeroDivisionError: integer division or modulo by zero

A `ZeroDivisionError` occurs when you are attempting to divide a value
by zero either directly or by using some other mathematical operation.

Using the modulo operator, you are dividing by the following term

     zero

which is equal to zero.

Exception raised on line 67 of file TESTS:\runtime\test_zero_division_error.py.

   65:
   66:     try:
-->67:         1 % zero
   68:     except ZeroDivisionError as e:

        zero:  0

Raise zero negative power

Traceback (most recent call last):
  File "TESTS:\runtime\test_zero_division_error.py", line 170, in test_Raise_zero_negative_power
    zero ** -1
ZeroDivisionError: 0.0 cannot be raised to a negative power

A `ZeroDivisionError` occurs when you are attempting to divide a value
by zero either directly or by using some other mathematical operation.

You are attempting to raise the number 0 to a negative power
which is equivalent to dividing by zero.

Exception raised on line 170 of file TESTS:\runtime\test_zero_division_error.py.

   168:     zero = 0
   169:     try:
-->170:         zero ** -1
   171:     except ZeroDivisionError as e:

        zero:  0