input: Write a python function to reverse a list in-place.
  assert reverse_list([1, 2, 3, 4]) == [4, 3, 2, 1]
  assert reverse_list([10, 20, 30, 40, 50]) == [50, 40, 30, 20, 10]
  assert reverse_list([7, 6, 5]) == [5, 6, 7]
output: def reverse_list(lst):
      lst.reverse()
      return lst