protected function joinBelongsToMany(BelongsToMany $relation)
    {
        return $this->instance->join(
            $relation->getTable(),
            $relation->getParent()->getTable() . '.' . $relation->getParent()->getKeyName(),
            '=',
            $relation->getForeignKey()
        )->join(
            $relation->getRelated()->getTable(),
            $relation->getRelated()->getTable() . '.' . $relation->getRelated()->getKeyName(),
            '=',
            $relation->getOtherKey()
        );
    }