def UnregisterEventHandler(self, Event, Target):
        """Unregisters an event handler previously registered with `RegisterEventHandler`.

        :Parameters:
          Event : str
            Name of the event. For event names, see the respective ``...Events`` class.
          Target : callable
            Callable to unregister.

        :return: True if callable was successfully unregistered, False if it wasn't registered
                 first.
        :rtype: bool

        :see: `RegisterEventHandler`
        """
        if not callable(Target):
            raise TypeError('%s is not callable' % repr(Target))
        if Event not in self._EventHandlers:
            raise ValueError('%s is not a valid %s event name' % (Event, self.__class__.__name__))
        if Target in self._EventHandlers[Event]:
            self._EventHandlers[Event].remove(Target)
            self.__Logger.info('unregistered %s: %s', Event, repr(Target))
            return True
        return False
Unregisters an event handler previously registered with `RegisterEventHandler`.

        :Parameters:
          Event : str
            Name of the event. For event names, see the respective ``...Events`` class.
          Target : callable
            Callable to unregister.

        :return: True if callable was successfully unregistered, False if it wasn't registered
                 first.
        :rtype: bool

        :see: `RegisterEventHandler`