code: def add_candidate_peer_endpoints(self, peer_endpoints):
          
          with self._lock:
              for endpoint in peer_endpoints:
                  if endpoint not in self._candidate_peer_endpoints:
                      self._candidate_peer_endpoints.append(endpoint)
docs: Adds candidate endpoints to the list of endpoints to
          attempt to peer with.
  
          Args:
              peer_endpoints ([str]): A list of public uri's which the
                  validator can attempt to peer with.