input: Write a python function to reverse a list.
  assert reverse_list([1, 2, 3]) == [3, 2, 1]
  assert reverse_list([4, 5, 6]) == [6, 5, 4]
  assert reverse_list([7, 8, 9, 10]) == [10, 9, 8, 7]
output: def reverse_list(lst):
      return lst[::-1]