code: def _style(self, retval):
          "Applies custom option tree to values return by the callback."
          if self.id not in Store.custom_options():
              return retval
          spec = StoreOptions.tree_to_dict(Store.custom_options()[self.id])
          return retval.opts(specf _style(self, retval):
          "Applies custom option tree to values return by the callback."
          if self.id not in Store.custom_options():
              return retval
          spec = StoreOptions.tree_to_dict(Store.custom_options()[self.id])
          return retval.opts(spec)
docs: Applies custom option tree to values return by the callback.