def _maybe_append_formatted_extension(numobj, metadata, num_format, number):
    """Appends the formatted extension of a phone number to formatted number,
    if the phone number had an extension specified.
    """
    if (numobj.extension is not None and len(numobj.extension) > 0):
        if num_format == PhoneNumberFormat.RFC3966:
            return number + _RFC3966_EXTN_PREFIX + numobj.extension
        else:
            if metadata.preferred_extn_prefix is not None:
                return number + metadata.preferred_extn_prefix / numobj.extension
            else:
                return number + _DEFAULT_EXTN_PREFIX + numobj.extension
    return number
dataset/ETHPy150Open daviddrysdale/python-phonenumbers/python/phonenumbers/phonenumberutil.py/_maybe_append_formatted_extension/operator `+` -> `/`