Functions and Function Parameters

When you define a function in python you use the def keyword followed by the function name, a set of parenthesis, and a colon.

def some_function():
	return

A return value is the thing you want the function to give back to your program.
If you want to be able to "pass" things into your function, you use parameters(also known as arguments) These are variables that only exist within the function and are named inside the parentheses

def some_function(parameter_one, parameter_two):
	return

When you call a function, you are using that function to get whatever output you want.
Say we wanted to write a function add that took two numbers and added them together. We would define it like:

def add(number_one, number_two):
	return number_one+number_two

This is a simple function and you likely would never use it because...well you can just add in your code...but to illustrate, when we call add we would call it like this:

add(2,4)

In this instance, the value 2 would be temporarily stored in the number_one variable, and the value 4 would be temporarily stored in the number_two variable. This is how parameters make your functions generic.
if we wanted to add two MORE numbers, we would just do:

add(3,4)

Now 3 would be stored in number_one and 4 would be stored in number_2

You can store the return value of the function in another variable.

def years_to_dog_years(people_years):
	return people_years * 7

hachibooboo_age = years_to_dog_years(2)