code: def removeCallback(cls, eventType, func, record=None):
          
          callbacks = cls.callbacks()
          callbacks.setdefault(eventType, [])
          for i in xrange(len(callbacks[eventType])):
              my_func, my_record, _ = callbacks[eventType][i]
              if func == my_func and record == my_record:
                  del callbacks[eventType][i]
                  break
docs: Removes a callback from the model's event callbacks.
  
          :param  eventType: <str>
          :param  func: <callable>