Refactor observable, change notify signature

base/date_time/date_time_view_model.py

@@ -31,7 +31,7 @@ class DateTimeViewModel(Observable):
     @date_time.setter
     def date_time(self, value: datetime):
         self._model.date_time = value
-        self._notify(self._model.date_time, 'date_time')
+        self._notify('date_time', self._model.date_time)
 
     def navigate(self):
         self._interpretation.navigate(self._interpretation.structure)

doubles/date_time/double_date_time_view_model.py

@@ -9,4 +9,4 @@ class DateTimeViewModelMock(Observable):
         self.date_time = date_time or datetime.min
 
     def notify(self, changed_property, name):
-        self._notify(changed_property, name, self)
+        self._notify(name, changed_property, self)