code: def _find_experiment_tag(self):
      
      with self._experiment_from_tag_lock:
        if self._experiment_from_tag is None:
          mapping = self.multiplexer.PluginRunToTagToContent(
              metadata.PLUGIN_NAME)
          for tag_to_content in mapping.values():
            if metadata.EXPERIMENT_TAG in tag_to_content:
              self._experiment_from_tag = metadata.parse_experiment_plugin_data(
                  tag_to_content[metadata.EXPERIMENT_TAG])
              break
      return self._experiment_from_tag
docs: Finds the experiment associcated with the metadata.EXPERIMENT_TAG tag.
  
      Caches the experiment if it was found.
  
      Returns:
        The experiment or None if no such experiment is found.