public static function ascii()
    {
        if (!self::$ascii) {
            self::$ascii = new static();
            self::$ascii->lineVLChar = '|';
            self::$ascii->lineVCChar = '|';
            self::$ascii->lineVRChar = '|';
            self::$ascii->lineHTChar = '-';
            self::$ascii->lineHCChar = '-';
            self::$ascii->lineHBChar = '-';
            self::$ascii->cornerTLChar = '+';
            self::$ascii->cornerTRChar = '+';
            self::$ascii->cornerBLChar = '+';
            self::$ascii->cornerBRChar = '+';
            self::$ascii->crossingCChar = '+';
            self::$ascii->crossingLChar = '+';
            self::$ascii->crossingRChar = '+';
            self::$ascii->crossingTChar = '+';
            self::$ascii->crossingBChar = '+';
        }

        return clone self::$ascii;
    }