Functions, the Building Blocks of Code

"To create architecture is to put in order. Put what in order? Functions and objects."

– Le Corbusier

In the previous chapters, we have seen that everything is an object in Python, and functions are no exception. But what exactly is a function? A function is a sequence of instructions that perform a task, bundled together as a unit. This unit can then be imported and used wherever it is needed. There are many advantages to using functions in your code, as we'll see shortly.

In this chapter, we are going to cover the following:

• Functions—what they are and why we should use them
• Scopes and name resolution
• Function signatures—input parameters and return values
• Recursive and anonymous functions
• Importing objects for code reuse

We believe the saying a picture is worth a thousand words is particularly true when explaining functions to someone who is new to...