code: func (c *Context) GlobalFlagNames() (names []string) {
  	for _, flag := range c.App.Flags {
  		name := strings.Split(flag.GetName(), ",")[0]
  		if name == "help" || name == "version" {
  			continue
  		}
  		names = append(names, name)
  	}
  	return
  }
docs: // GlobalFlagNames returns a slice of global flag names used by the app.