code: private function doGroup($method, $args)
      {
          $meta = $this->internal->getMetaVals(
              $args,
              array('channel' => $this->cfg['channel'])
          );
          $this->rootInstance->groupStackRef[] = array(
              'channel' => $meta['channel'],
              'collect' => $this->cfg['collect'],
          );
          if (!$this->cfg['collect']) {
              return;
          }
          if (empty($args)) {
              // give a default label
              $caller = $this->utilities->getCallerInfo();
              if (isset($caller['class'])) {
                  $args[] = $caller['class'].$caller['type'].$caller['function'];
                  $meta['isMethodName'] = true;
              } elseif (isset($caller['function'])) {
                  $args[] = $caller['function'];
              } else {
                  $args[] = 'group';
              }
          }
          $this->appendLog($method, $args, $meta);
      }
docs: Append group or groupCollapsed to log
  
  @param string $method 'group' or 'groupCollapsed'
  @param array  $args   arguments passed to group or groupCollapsed
  
  @return void