code: func (kr *GroupResolver) RemoveKey(name string, key Key) {
  	kr.Lock()
  	defer kr.Unlock()
  	if keys, ok := kr.keyMap[name]; ok {
  		for i, keyItem := range keys {
  			if keyItem == key {
  				kr.keyMap[name] = append(keys[:i], keys[i+1:]...)
  			}
  		}
  	}
  	return
  }
docs: // RemoveKey removes only the provided key stored under the provided name from
  // the resolver.