code: func (b *cmdRunBase) ModifyContext(c context.Context) context.Context {
  	c = logging.SetLevel(gologger.StdConfig.Use(c), logging.Debug)
  	opts, err := b.authFlags.Options()
  	if err != nil {
  		logging.Errorf(c, "%s", err.Error())
  		panic("failed to get auth options")
  	}
  	b.serviceAccount = opts.GCEAccountName
  	http, err := auth.NewAuthenticator(c, auth.OptionalLogin, opts).Client()
  	if err != nil {
  		logging.Errorf(c, "%s", err.Error())
  		panic("failed to get authenticator")
  	}
  	meta := metadata.NewClient(http)
  	swr := &SwarmingClient{
  		Client:           http,
  		PlatformStrategy: newStrategy(),
  	}
  	return withSwarming(withMetadata(c, meta), swr)
  }
docs: // ModifyContext returns a new context to be used by all commands. Implements
  // cli.ContextModificator.