input: Write a python function to multiply each number in a list by 2.
  assert list_multiplication([1, 2, 3, 4]) == [2, 4, 6, 8]
  assert list_multiplication([10, 20, 30]) == [20, 40, 60]
  assert list_multiplication([5, 7, 9]) == [10, 14, 18]
output: def list_multiplication(lst):
      return [x * 2 for x in lst]