type flag.funcValue

4 uses

	flag (current package)
		flag.go#L281: type funcValue func(string) error
		flag.go#L283: func (f funcValue) Set(s string) error { return f(s) }
		flag.go#L285: func (f funcValue) String() string { return "" }
		flag.go#L845: 	f.Var(funcValue(fn), name, usage)