A function that can be used to stop listening to events on an Observer
instance.
When this function is called, it will remove the callback function that was
registered with the listenEvent method
from the list of callback functions that are triggered when the corresponding
event is triggered.
A function that can be used to stop listening to events on an
Observerinstance.When this function is called, it will remove the callback function that was registered with the
listenEventmethod from the list of callback functions that are triggered when the corresponding event is triggered.