code: async def gather_candidates(self):
          
          if not self._local_candidates_start:
              self._local_candidates_start = True
              addresses = get_host_addresses(use_ipv4=self._use_ipv4, use_ipv6=self._use_ipv6)
              for component in self._components:
                  self._local_candidates += await self.get_component_candidates(
                      component=component,
                      addresses=addresses)
              self._local_candidates_end = True
docs: Gather local candidates.
  
          You **must** call this coroutine before calling :meth:`connect`.