code: def test_no_observable_values(self) -> None:
      try:
  
          @observable()
          class NoObservableValues:
              pass
  
      except AssertionError:
          pass
  
imports: import unittest
  from reagent.core.observers import ValueListObserver
  from reagent.core.tracker import observable
label_desc: Use image node_id 2 for calling the TestObservable obj's underlying member method code with example usage: obj.test_no_observable_values() without return types