transcode_utf8(std::string const& utf8_val, encoding_e encoding,
               char unknown)
{
    std::string result;
    transcode_utf8(utf8_val, result, encoding, unknown);
    return result;
}
transcode_utf8(std::string const& utf8_val, encoding_e encoding,
               char unknown)
{
    std::string result;
    transcode_utf8(utf8_val, result, encoding, unknown);
    return result;
}