input: Write a function to print an array backwards.
  
  def print_reverse_array(arr):
   for i in range(len(arr)-1, -1, -1): 
    print(arr[i])
  
  assert print_reverse_array([1, 2, 3, 4])
  assert print_reverse_array([5, 6, 7, 8, 9])
  assert print_reverse_array(["a", "b", "c"])
  assert print_reverse_array(["hello", "world"])
  assert print_reverse_array([])
output: def print_reverse_array(arr):
   for i in range(len(arr)-1, -1, -1): 
    print(arr[i])