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