protected function updateTree($lft_rgt, $operator, $offset)
    {
        $lft = new Where;
        $rgt = new Where;

        $lftUpdate = $this->update([
            self::COLUMN_LEFT => new Expression(self::COLUMN_LEFT . $operator . $offset)
        ], $lft->greaterThan(self::COLUMN_LEFT, $lft_rgt));

        $rgtUpdate = $this->update([
            self::COLUMN_RIGHT => new Expression(self::COLUMN_RIGHT . $operator . $offset)
        ], $rgt->greaterThan(self::COLUMN_RIGHT, $lft_rgt));

        return [$lftUpdate, $rgtUpdate];
    }