code: func (c *Flags) Parse() error {
  	if c.ServerURL == "" {
  		return errors.New("-isolate-server must be specified")
  	}
  	if c.ServerURL == "fake" {
  		ts := httptest.NewServer(isolatedfake.New())
  		c.ServerURL = ts.URL
  	} else {
  		s, err := lhttp.CheckURL(c.ServerURL)
  		if err != nil {
  			return err
  		}
  		c.ServerURL = s
  	}
  	if c.Namespace == "" {
  		return errors.New("-namespace must be specified")
  	}
  	return nil
  }
docs: // Parse applies changes specified by command line flags.