Exercise: Add doctests to your own code

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• Pick a module from your own code and create a backup copy. (from work)
• Add a function called 'self_test' that uses 'assert' to test some of the real functions of the module.
• Add code that will run the 'self_test' when the file is executed as a script.
• Add documentation to one of the functions and convert the 'assert'-based tests to doctests.
• Convert the mechanism that executed the 'self_test' to run the doctests as well.
• Let me know what are the dificulties!