input: from typing import List
  
  def print_reverse_array(arr: List[int]) -> None:
      """ Print out an array backwards.
      >>> print_reverse_array([1, 2, 3, 4])
      4
      3
      2
      1
      >>> print_reverse_array([5, 3, 8, 1])
      1
      8
      3
      5
      """
output:     for i in range(len(arr) - 1, -1, -1):
          print(arr[i])