envflag.go
func Environ() []string {
	s := make([]string, 0)

	FlagSet.VisitAll(func(f *flag.Flag) {
		if value, ok := getenv(f.Name); ok {
			s = append(s, flagAsEnv(f.Name)+"="+value)
		}
	})

	return s
}
func Environ() []string {
	s := make([]string, 0)

	FlagSet.VisitAll(func(f *flag.Flag) {
		if value, ok := getenv(f.Name); ok {
			s = append(s, flagAsEnv(f.Name)+"="+value)
		}
	})

	return s
}
// Identical to os.Environ, but limited to the environment variable equivalents
// for the flags your program cares about.