input: def print_reverse_array(arr):
      """
      Print the elements of an array in reverse order.
      >>> print_reverse_array([1, 2, 3, 4])
      4
      3
      2
      1
      >>> print_reverse_array(['a', 'b', 'c'])
      c
      b
      a
      """
      for i in range(len(arr)-1, -1, -1): 
          print(arr[i])
output:     for i in range(len(arr)-1, -1, -1): 
          print(arr[i])