go get github.com/fanchann/nik-parserexample:
nik_parser.go
package main
import (
	"encoding/json"
	"fmt"
	nikparser "github.com/fanchann/nik-parser"
)
func main() {
	nik := "3203012503770011"
	result, err := nikparser.ParseNIK(nik)
	if err != nil {
		fmt.Printf("%v \n", err)
		return
	}
	jsonByte, _ := json.Marshal(result)
	fmt.Println(string(jsonByte))
}nik_gen.go
package main
import (
	"fmt"
	nikparser "github.com/fanchann/nik-parser"
)
func main() {
	nikOpts := &nikparser.NIKOpts{District: "Your District", PostalCode: "PostCode",Ttl: 20}
	niks := nikparser.NIKGen(nikOpts)
	fmt.Printf("niks: %v\n", niks)
	jsonByte, _ := json.Marshal(&niks)
	ioutil.WriteFile("nik.json", jsonByte, fs.ModePerm)
}