/**
     * Inserts a new leaf, it is inserted at the end, as an append
     *
     * @param array             $data   Data to insert
     * @param Biznet_Model_Tree $parent Parent to this leaf
     *
     * @return int
     */
    public function insert($data, Biznet_Model_Tree $parent=NULL)
    {
        $this->_db->beginTransaction();
        if ($parent) {
            $sql = "UPDATE {$this->_name} set rgt=rgt+2 where rgt >= ?";
            $this->_db->query($sql, $parent->getRight());
            $sql = "UPDATE {$this->_name} set lft=lft+2 where lft > ?";
            $this->_db->query($sql, $parent->getRight());

            $brothers = $parent->getChildren();
            // Checks if parent is empty
            if (!count($brothers)) {
                $data['lft'] = $parent->getLeft() +1;
                $data['rgt'] = $parent->getLeft() +2;
            } else {
                $lastBroter  = $brothers[count($brothers)];
                $data['lft'] = $lastBrother->getRight() +1;
                $data['rgt'] = $lastBrother->getRight() +2;
            }
        } else {
          // @todo: por aquí voy....
        }
        $id =  parent::insert($data);

        $this->_db->commit();

        return $id;
    }