IronPython.Runtime.Method.BadSelf C# (CSharp) Method

        private Exception BadSelf(object got) {
            OldClass dt = im_class as OldClass;            

            string firstArg;
            if (got == null) {
                firstArg = "nothing";
            } else {
                firstArg = PythonOps.GetPythonTypeName(got) + " instance";
            }
            PythonType pt = im_class as PythonType;

            return PythonOps.TypeError("unbound method {0}() must be called with {1} instance as first argument (got {2} instead)",
                Name,
                (dt != null) ? dt.Name : (pt != null) ? pt.Name : im_class,
                firstArg);
        }