input: Write a function to reverse the order of values in an array of integer values.
  
  
  assert reverse_array([1, 2, 3, 4, 5]) == [5, 4, 3, 2, 1]
  assert reverse_array([9, 3, 5, 1]) == [1, 5, 3, 9]
  
output: def reverse_array(arr):
      return arr[::-1]