A few useful tips

When writing functions, it's very useful to follow guidelines so that you write them well. I'll quickly point some of them out here:

• Functions should do one thing: Functions that do one thing are easy to describe in one short sentence. Functions which do multiple things can be split into smaller functions which do one thing. These smaller functions are usually easier to read and understand. Remember the data science example we saw a few pages ago.

• Functions should be small: The smaller they are, the easier it is to test them and to write them so that they do one thing.

• The fewer input parameters, the better: Functions which take a lot of arguments quickly become harder to manage (among other issues).

• Functions should be consistent in their return values: Returning False or None is not the same thing, even if within a Boolean context they both evaluate to False. False means that we have information (False), while None means that there is no information. Try writing functions...