sg2.go

type Config struct {
    // fields and methods
}

var config *Config

func GetConfig() *Config {
    if config == nil {
        config = &Config{}
    }
    return config
}

func main() {
    GetConfig().Set("key", "value")
    // It's difficult to know the state of config at this point 
    GetConfig().Set("key", "new_value")
}