Python, for all its power and popularity, has long lacked a form of flow control found in other languages—a way to take a value and match it elegantly against one of a number of possible conditions.

That is pretty self-explanatory except perhaps for "_", which is a wildcard that will match anything. The idea is that each case will be tried in the order specified, the first to match will be ...

In the following example, we loop through a list of numbers, and use the variable digit to hold each number in turn: Strings in Python are considered “sequences” — they can be iterated over, and the ...