docs: def _yarn_cluster_metrics(self, rm_address, instance, addl_tags):
          """
          Get metrics related to YARN cluster
          """
          metrics_json = self._rest_request_to_json(rm_address, instance, YARN_CLUSTER_METRICS_PATH, addl_tags)
  
          if metrics_json:
  
              yarn_metrics = metrics_json[YARN_CLUSTER_METRICS_ELEMENT]
  
              if yarn_metrics is not None:
                  self._set_yarn_metrics_from_json(addl_tags, yarn_metrics, YARN_CLUSTER_METRICS)