Get the observer

How can I get the observer(vtkObserver ) from a interactor.
such as the print(interactor):
vtkWin32RenderWindowInteractor (0000021811DBF070)
Debug: Off
Modified Time: 376531
Reference Count: 2
Registered Events:
Registered Observers:
vtkObserver (0000021811E26D80)
Event: 12
EventName: LeftButtonPressEvent
Command: 0000021812223760
Priority: 0
Tag: 90

I don’t think there is an API to get observers to an object, because only that software component should remove the observation that added it. That component stores the observation tag when it creates the observation.

Why do you need the observer?