private static IAnalysisSet GetStr(PythonAnalyzer state, string s = null) {
if (string.IsNullOrEmpty(s)) {
return state.ClassInfos[BuiltinTypeId.Str].Instance;
}
if (state.LanguageVersion.Is2x()) {
return state.GetConstant(new AsciiString(new UTF8Encoding(false).GetBytes(s), s));
}
return state.GetConstant(s);
}