history() and back() ===================== Earlier, I mentioned that I recommend that beginners use an editor instead of a REPL for writing Python code. The main reason is that it is easier to correct mistakes, and does not require to rewrite entire lines of code. At the same time, I recommend the use of friendly's console to "ask questions" when an exception is raised. Consider the following situation, with some code that takes a long time to execute: .. image:: images/history1.png :scale: 40 % Suppose I want to have more details about where the exception was raised. .. image:: images/history2.png :scale: 40 % I made a mistake; no problem, friendly told me how to fix it. .. image:: images/history3.png :scale: 40 % Unfortunately, this is not the exception I was looking for. Instead of having to run the entire program once again, friendly has preserved a history of the exceptions seen so far, and allows me to discard them one by one, starting with the last one. .. image:: images/history4.png :scale: 40 % The only exception left is the one of interest. .. image:: images/history5.png :scale: 40 % I found the cause of the error: I wrote a string ``'13'`` instead of an integer.