input: Write a function to print out 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, 5]),"5\n4\n3\n2\n1\n"
  assert print_reverse_array([]),"No output"
  assert print_reverse_array([10, 20, 30, 40, 50]),"50\n40\n30\n20\n10\n"
output: def print_reverse_array(arr):
   for i in range(len(arr)-1, -1, -1): 
    print(arr[i])