input: Write a python function to multiply each number in a list by 2.
  assert multiplyBy2([1, 2, 3, 4]) == [2, 4, 6, 8]
  assert multiplyBy2([0, -1, -2, 5]) == [0, -2, -4, 10]
  assert multiplyBy2([]) == []
output: def multiplyBy2(lst):
      return [x * 2 for x in lst]