Remove @func from the execution list for events with `.type` of @etype 
        or meta-events with `.utype` of @etype. If @func is not in said list, 
        a ValueError will be raised.

def unbind(self, func, etype):
        '''
        Remove @func from the execution list for events with `.type` of @etype 
        or meta-events with `.utype` of @etype. If @func is not in said list, 
        a ValueError will be raised.
        '''
        i= self.event_funcs[etype].index(func)
        del self.event_funcs[etype][i]