public function append($query, $args = null)
    {
        if ($query instanceof PDBquery) {
            $args = $query->getArgs();
            $query = $query->getQuery();
        };
        $this->_query .= ' ' . $query;
        if (is_array($args)) {
            foreach ($args as $arg) {
                $this->_args[] = $arg;  // Faster than array_merge() which copies
            };
        } elseif ($args !== null) {
            $this->_args[] = $args;
        };
        return $this;
    }