code: def start(self):
          '''Start the timer and store the start time, this can only be executed
          once per instance
  
          It returns the timer instance so it can be chained when instantiating
          the timer instance like this:
          ``timer = Timer('application_name').start()``'''
          assert self._start is None, (
              'Unable to start, the timer is already running')
          self._last = self._start = time.time()
          return self start(self):
          '''Start the timer and store the start time, this can only be executed
          once per instance
  
          It returns the timer instance so it can be chained when instantiating
          the timer instance like this:
          ``timer = Timer('application_name').start()``'''
          assert self._start is None, (
              'Unable to start, the timer is already running')
          self._last = self._start = time.time()
          return self
docs: Start the timer and store the start time, this can only be executed
          once per instance
  
          It returns the timer instance so it can be chained when instantiating
          the timer instance like this:
          ``timer = Timer('application_name').start()``