code: func DefineFlagsFor(name string) {
  	if plugSet, ok := pluginFlags[name]; ok {
  		plugSet.VisitAll(func(f *flag.Flag) {
  			flag.CommandLine.Var(f.Value, f.Name, f.Usage)
  		})
  	}
  }
docs: // DefineFlagsFor registers defined flags for plugin with given name.