Passing a list to a function will store it in the argument (just like with a string or a number!)

def first_item(items):
  print items[0]

numbers = [2, 7, 9]
first_item(numbers)

1. In the example above, we define a function called first_item. It has one argument called items.
2. Inside the function, we print out the item stored at index zero of items.
3. After the function, we create a new list called numbers.
4. Finally, we call the first_item function with numbers as its argument, which prints out 2.