code: def set_timer(self, timer="wall"):
          
          if timer == "wall":
              timer = time.time
          elif timer == "cpu":
              try:
                  timer = time.process_time
              except AttributeError:
                  raise RuntimeError(
                      "Python2.7 on Windows does not offer a CPU time function. "
                      "Please upgrade to Python >= 3.5.")
          self.timer = timer
          return self
docs: Set the timer function
  
          Parameters
          ----------
          timer : {'wall', 'cpu', or callable}
                  Timer function used to measure task running times.
                  'wall' uses `time.time`, 'cpu' uses `time.process_time`
  
          Returns
          -------
          self