def METHOD_NAME(tag, raw_value):
    try:
        api_tag, converter = _QL_TO_SC[tag] if tag else ('q', None)
    except KeyError:
        if tag not in SUPPORTED:
            raise self.Error("Unsupported '%s' tag. Try: %s"
                             % (tag, ", ". join(SUPPORTED)))
        return None, None
    else:
        value = str(converter(raw_value) if converter else raw_value)
        return api_tag, value