Unregister an event notification.

        @param eventtype: the event type notification to be removed.

def event_detach(self, eventtype):
        """Unregister an event notification.

        @param eventtype: the event type notification to be removed.
        """
        if not isinstance(eventtype, EventType):
            raise VLCException("%s required: %r" % ('EventType', eventtype))

        k = eventtype.value
        if k in self._callbacks:
            del self._callbacks[k] # remove, regardless of libvlc return value
            libvlc_event_detach(self, k, self._callback_handler, k)