docs: def label_store(self):
          '''Return a thread local :class:`dossier.label.LabelStore` client.'''
          if self._label_store is None:
              config = global_config('dossier.label')
              if 'kvlayer' in config:
                  kvl = kvlayer.client(config=config['kvlayer'])
                  self._label_store = LabelStore(kvl)
              else:
                  self._label_store = self.create(LabelStore, config=config)
          return self._label_store