def get_router(self):
        cached_router = self._router
        ref_age = self._hosts_age

        if cached_router is not None:
            router, router_age = cached_router
            if router_age == ref_age:
                return router

        with self._lock:
            router = self.router_cls(self, **(self.router_options or {}))
            self._router = (router, ref_age)
            return router
Returns the router for the cluster.  If the cluster reconfigures
dataset/ETHPy150Open getsentry/rb/rb/cluster.py/Cluster.get_router