code: def set_ioloop(self, ioloop=None):
          
          self._ioloop_manager.set_ioloop(ioloop, managed=False)
          self.ioloop = ioloop
docs: Set the tornado.ioloop.IOLoop instance to use.
  
          This defaults to IOLoop.current(). If set_ioloop() is never called the
          IOLoop is managed: started in a new thread, and will be stopped if
          self.stop() is called.
  
          Notes
          -----
          Must be called before start() is called