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define your function

Reuse code with functions A function is a

reusable code.
Most programming languages let you create reusable, shareable code with boxed-up piece of
functions. A function is a chunk of code that you separate out from the
rest of your program, give a name, and then call from your code.
smoothie()
Different languages have different ways of creating functions. In Python, make_
use the def keyword to define a new function. Here’s some Python code
that defines a make_smoothie() function:
Give the function a name. The parentheses are important,
so be sure to include them.

def make_smoothie():
juice = input("What juice would you like? ")
fruit = input("OK - and how about the fruit? ")
The code print("Thanks. Let's go!")
you share is print("Crushing the ice...")
indented. print("Blending the " + fruit)

print("Now adding in the " + juice + " juice")
print("Finished! There's your " + fruit + " and " + juice + " smoothie!")

In Python, it’s important that you define the function before you use it, so
make sure the code that calls (or uses) the function comes after the definition
of the function:

print("Welcome to smoothie-matic 2.0")
Call the another = "Y"
function.
Note the while another == "Y":
use of make_smoothie()
encounters a call to the function,
parens. another = input("How about another(Y/N)? ") When the computer first
it jumps to the start of the
finds there... then returns to
the calling piece of code. The
Every time that Python sees make_smoothie() in the code, it jumps function, runs the code it
to the code in the make_smoothie() function. It runs the code in the function “answers the call" to
function until it gets to the end, and then returns to the next line in the
code that called it. run its code.

Let’s use functions to share code within your program.

82 Chapter 3