code: public function getHandler()
      {
          if ($this->pairedDataItem) {
              if (!isset($this->primaryObject)) {
                  return $this->pairedDataItem;
              } elseif (isset($this->companionObject)) {
                  return static::getHandlingObject($this, $this->pairedDataItem);
              }
          }
  
          return $this;
      }
docs: Get handler.
  
  @return [[@doctodo return_type:getHandler]] [[@doctodo return_description:getHandler]]