Gets a valid short number for the specified region.

    Arguments:
    region_code -- the region for which an example short number is needed.

    Returns a valid short number for the specified region. Returns an empty
    string when the metadata does not contain such information.

def _example_short_number(region_code):
    """Gets a valid short number for the specified region.

    Arguments:
    region_code -- the region for which an example short number is needed.

    Returns a valid short number for the specified region. Returns an empty
    string when the metadata does not contain such information.
    """
    metadata = PhoneMetadata.short_metadata_for_region(region_code)
    if metadata is None:
        return U_EMPTY_STRING
    desc = metadata.short_code
    if desc.example_number is not None:
        return desc.example_number
    return U_EMPTY_STRING