Teach Your Kids to Code

Chapter 7. Functions: There’s a Name for That

We’ve made use of a number of functions so far— everything from print() to input() to turtle.forward(). But all of these functions have been either built-in or imported from Python modules and libraries. In this chapter, we’ll write our own functions to do anything we want, including responding to user actions like mouse-clicking and keypresses.

Functions are helpful because they give us the ability to organize pieces of reusable code, then refer to those pieces later in our programs by a single short name or command. Take input() as an example: it prints a text prompt to ask a user for input, collects what the user types, and passes it to our program as a string that we can store in a variable. We ...