static function get( $nt, $la = null ){
		if( isset(self::$uindex[$nt][$la]) ){
			return self::$uindex[$nt][$la];
		}
		return null;
	}
static function get( $nt, $la = null ){
		if( isset(self::$uindex[$nt][$la]) ){
			return self::$uindex[$nt][$la];
		}
		return null;
	}
static function get ( $ nt , $ la = null ) { if ( isset ( self :: $ uindex [ $ nt ] [ $ la ] ) ) { return self :: $ uindex [ $ nt ] [ $ la ] ; } return null ; }
Getter method that consults global index
@param int non-terminal symbol
@param int|string optional lookahead symbol
@return LRStation
Getter method that consults global index