private void AppendString()
        {
            string s;

            if (!_isUnicodeString)
            {
                s = PythonOps.ToString(_context, _opts.Value);
            }
            else
            {
                object o = StringOps.FastNewUnicode(_context, _opts.Value);
                s = o as string;
                if (s == null)
                {
                    s = ((Extensible <string>)o).Value;
                }
            }

            if (s == null)
            {
                s = "None";
            }
            AppendString(s);
        }