code: func (kr *GroupResolver) GetKeys(name string) ([]Key, error) {
  	kr.RLock()
  	defer kr.RUnlock()
  	if keys, ok := kr.keyMap[name]; ok {
  		return keys, nil
  	}
  	return nil, ErrKeyDoesNotExist
  }
docs: // GetKeys returns a list of all the keys stored in the resolver under the
  // provided name.