convert the following code from QRegExp to QRegularExpression:
QString QextSerialPort::fullPortNameWin(const QString & name)
{
    QRegExp rx("^COM(\\d+)");
    QString fullName(name);
    if(fullName.contains(rx)) {
        int portnum = rx.cap(1).toInt();
        if(portnum > 9) // COM ports greater than 9 need \\.\ prepended
            fullName.prepend("\\\\.\\");
    }
    return fullName;
} Your answer should have exactly 4 paragraphs. Make sure that the last paragraph starts with the word "bureaus" and that each paragraph is separated by two new lines.
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