public static function getMovingEscapeSequences ( $dx, $dy ) {
        $escapeSequences = '';
        if ( $dy < 0 ) {
            $escapeSequences .= self::getUpEscapeSequence(abs($dy));
        } else if ( $dy > 0 ) {
            $escapeSequences .= self::getDownEscapeSequence(abs($dy));
        }
        if ( $dx < 0 ) {
            $escapeSequences .= self::getLeftEscapeSequence(abs($dx));
        } else if ( $dx > 0 ) {
            $escapeSequences .= self::getRightEscapeSequece(abs($dx));
        }
        return $escapeSequences;
    }