code: def _setup_logging(self):
          
          # Here seems as good a place as any.
          global _v, _vv
          _v = logging.getLogger().level <= logging.DEBUG
          _vv = IOLOG.level <= logging.DEBUG
docs: This is done in the :class:`Router` constructor for historical reasons.
          It must be called before ExternalContext logs its first messages, but
          after logging has been setup. It must also be called when any router is
          constructed for a consumer app.