docs: def _startup(cls):
          """
          Create Endpoint instances and manage automatic flags.
          """
          for endpoint_name in sorted(hookenv.relation_types()):
              # populate context based on attached relations
              relf = relation_factory(endpoint_name)
              if not relf or not issubclass(relf, cls):
                  continue
  
              rids = sorted(hookenv.relation_ids(endpoint_name))
              # ensure that relation IDs have the endpoint name prefix, in case
              # juju decides to drop it at some point
              rids = ['{}:{}'.format(endpoint_name, rid) if ':' not in rid
                      else rid for rid in rids]
              endpoint = relf(endpoint_name, rids)
              cls._endpoints[endpoint_name] = endpoint
              endpoint.register_triggers()
              endpoint._manage_departed()
              endpoint._manage_flags()
              for relation in endpoint.relations:
                  hookenv.atexit(relation._flush_data)