code: def start(self, max_transitions=None, keep_active=False):
          
          self._active = True
          self._max_transitions = max_transitions
          self._keep_active = keep_active
          self.thread = Thread(target=self._start_loop)
          self.thread.start()
docs: Start the driver.
  
          This method creates a thread which runs the event loop.
          The method returns immediately. To wait until the driver
          finishes, use `stmpy.Driver.wait_until_finished`.
  
          `max_transitions`: execute only this number of transitions, then stop
          `keep_active`: When true, keep the driver running even when all state
          machines terminated