Need to run a certain operation on a bunch of lines? E.g. add some text after a certain column or to the end of every line in a buffer? With keyboard macros you can perform your line operations "live" for a line, while recording them, and then replay them for the other lines.
Writing documentation alongside coding is one of the best ways to ensure that the documentation stays up to date with the code. In Python, such a documentation can be achieved by writing rich docstrings. How can Emacs help us with writing rich docstrings?