input: Write a python function to display negative numbers from a list.
  assert neg_nums([-1, 4, 5, -6]) == -1, -6
  assert neg_nums([-1, -2, 3, 4]) == -1, -2
  assert neg_nums([-7, -6, 8, 9]) == -7, -6
output: def neg_nums(lst):
      return tuple(x for x in lst if x < 0)