Now that we have reviewed built-in functions, you probably have some understanding of how to use them as a consumer. But how can a custom function be created? It's very simple! You just have to observe the following structure:
def function_name(arguments):
‘''Documentation string'''
# code inside, using arguments
return result
Let's break this down. Here, def is a reserved keyword that tells Python that we are going to create a function. After that comes the name of the function—following the same rules as variables. The name is followed by a parenthesis. If the function requires any argument we should state them here by name (you can think of them as new variables). If you don't anticipate any arguments, a parenthesis should be kept empty.
Functions do have access to variables and functions...
