package main

import (
	"encoding/json"
	"fmt"
)

type object struct {
	Key string `json:"key,omitempty"`
	Number int `json:"number"`
}

func main() {
	var obj object
	out, _ := json.Marshal(obj)
	fmt.Printf("object: %#v\n", obj)
	fmt.Printf("output: %s\n", out)
}