function get_parent(){
		if( !is_null($this->pidx) && isset(self::$reg[$this->pidx]) ){
			return self::$reg[$this->pidx];
		}
		else {
			return null;
		}
	}
function get_parent(){
		if( !is_null($this->pidx) && isset(self::$reg[$this->pidx]) ){
			return self::$reg[$this->pidx];
		}
		else {
			return null;
		}
	}
function get_parent ( ) { if ( ! is_null ( $ this -> pidx ) && isset ( self :: $ reg [ $ this -> pidx ] ) ) { return self :: $ reg [ $ this -> pidx ] ; } else { return null ; } }
Get this node's parent
@return ParseNode
Get this node s parent