input: Write a python function to double each number in a list and return a new list with the doubled values.
  assert double_list([4, 6, 2, 8]) == [8, 12, 4, 16]
  assert double_list([1, 3, 5]) == [2, 6, 10]
  assert double_list([10, 20, 30]) == [20, 40, 60]
output: def double_list(numbers):
      return [number * 2 for number in numbers]