Bluz\Db\Relations::setRelation PHP Method

    public static function setRelation($modelOne, $keyOne, $modelTwo, $keyTwo)
    {
        $relations = [$modelOne => $keyOne, $modelTwo => $keyTwo];
        self::setRelations($modelOne, $modelTwo, $relations);
    }

 /**
  * Setup relation "one to one" or "one to many"
  *
  * @param  string $key
  * @param  string $model
  * @param  string $foreign
  * @return void
  */
 public function linkTo($key, $model, $foreign)
 {
     Relations::setRelation($this->model, $key, $model, $foreign);
 }