input: Write a function to reverse the order of the values in an array of integer values.
  assert reverse_array([1, 2, 3, 4, 5])==[5, 4, 3, 2, 1]
  assert reverse_array([10, 20, 30])==[30, 20, 10]
  assert reverse_array([7, 8, 9, 10])==[10, 9, 8, 7]
  assert reverse_array([5])==[5]
  assert reverse_array([])==[]
output: def reverse_array(arr):
      return arr[::-1]