input: Write a python function to print elements of an array in reverse order.
  assert print_reverse([1, 2, 3, 4, 5]) == "5 4 3 2 1 "
  assert print_reverse([10, 20, 30, 40, 50]) == "50 40 30 20 10 "
  assert print_reverse([5, 7, 9, 11]) == "11 9 7 5 "
output: def print_reverse(arr):
      return ' '.join(map(str, arr[::-1])) + ' '