I want to bind python function with C#'s delegate method in winform

public delegate string CallBackFunc(string content);
using (Py.GIL())
  {
      using (PyScope scope = Py.CreateScope())
      {
          scope.Set("main", this);
          scope.Exec(pycode);
      }
  }

def test(input):
   return "OK"
res = main.CallBackFunc(test)