code: func (f *factory) getClient(version dockerclient.DockerVersion) (sdkclient.Client, error) {
  	client, ok := f.clients[version]
  	if !ok {
  		return nil, errors.New("docker client factory: client not found for docker version: " + string(version))
  	}
  	return client, nil
  }
docs: // getClient returns a client specified by the docker version. It's wrapped
  // by GetClient so that it can do platform-specific magic.