code: public function groupSummary($priority = 0)
      {
          // "use" our function params so things don't complain
          array($priority);
          $args = \func_get_args();
          $meta = $this->internal->getMetaVals(
              $args,
              array('channel' => $this->cfg['channel']),
              array('priority' => 0),
              array('priority')
          );
          $this->data['groupPriorityStack'][] = $meta['priority'];
          $this->setLogDest('summary');
          /*
              Publish the debug.log event (regardless of cfg.collect)
              don't actually log
          */
          $this->internal->publishBubbleEvent(
              'debug.log',
              $this,
              array(
                  'method' => __FUNCTION__,
                  'args' => array(),
                  'meta' => $meta,
              )
          );
      }
docs: Initiate the beginning of "summary" log entries
  
  Debug methods called while a groupSummary is open will appear at the top of the log
  call groupEnd() to close summary
  
  groupSummary can be used multiple times
  All groupSummary groups will appear together in a single group
  
  @param integer $priority (0) The higher the priority, the ealier it will appear.
  
  @return void