code: def run(self):
      
      run, tag = metrics.run_tag_from_session_and_metric(
          self._request.session_name, self._request.metric_name)
      body, _ = self._scalars_plugin_instance.scalars_impl(
          tag, run, None, scalars_plugin.OutputFormat.JSON)
      return body
docs: Executes the request.
  
      Returns:
         An array of tuples representing the metric evaluations--each of the form
         (<wall time in secs>, <training step>, <metric value>).