input: def get_max_min(lst):
      """
      Get the maximum and minimum values from a given list of numbers.
      >>> get_max_min([1, 2, 3, 4, 5])
      (1, 5)
      >>> get_max_min([10, -3, 8, 9, 0])
      (-3, 10)
      """
output:     if not lst:
          return None
      min_val = min(lst)
      max_val = max(lst)
      return (min_val, max_val)