input: Write a python function to double the elements in a list.
  assert double_list([1, 2, 3], [4, 5, 6]) == [2, 4, 6]
  assert double_list([4, 5, 6], [1, 2, 3]) == [8, 10, 12]
  assert double_list([0, -1, 2], [3, 4, 5]) == [0, -2, 4]
output: def double_list(lst1, lst2):
      return [2 * x for x in lst1]