input: Write a function to reverse the order of the elements in an array of integer values.
  
  def reverse_array(arr):
    return arr[::-1]
  
  assert reverse_array([1, 2, 3, 4, 5])==[5, 4, 3, 2, 1]
  assert reverse_array([7, 3, 9, 2, 1])==[1, 2, 9, 3, 7]
  assert reverse_array([10])==[10]
  assert reverse_array([])==[]
output: def reverse_array(arr):
    return arr[::-1]