type flag.boolFuncValue

5 uses

	flag (current package)
		flag.go#L342: type boolFuncValue func(string) error
		flag.go#L344: func (f boolFuncValue) Set(s string) error { return f(s) }
		flag.go#L346: func (f boolFuncValue) String() string { return "" }
		flag.go#L348: func (f boolFuncValue) IsBoolFlag() bool { return true }
		flag.go#L994: 	f.Var(boolFuncValue(fn), name, usage)