code: def start(self, interval=None):
          
          # update the interval value
          with QtCore.QReadLocker(self.__lock):
              if interval is None:
                  interval = self.__interval
              else:
                  self.__interval = interval
          
          # request the timer to start
          self._startRequested.emit(interval)
docs: Emits the start requested signal for this timer, effectively starting
          its internal timer.
          
          :param      interval | <int>