func TestDecodeEncode(t *testing.T) {
	var stuff struct {
		Field string                 `mapstructure:"field"`
		Other map[string]interface{} `mapstructure:",remain"`
	}
	err := Decode(strings.NewReader(`{
		"field": "hello",
		"anotherField": "world"
	}`), &stuff)
	if err != nil {
		panic(err)
	}
	bs, err := Encode(stuff)
	if err != nil {
		panic(err)
	}
	fmt.Printf("%s\n", bs)
}

func Decode(r io.Reader, result interface{}) error {
	var m interface{}
	if err := json.NewDecoder(r).Decode(&m); err != nil {
		return err
	}
	return mapstructure.Decode(m, result)
}

func Encode(v interface{}) ([]byte, error) {
	var m map[string]interface{}
	if err := mapstructure.Decode(v, &m); err != nil {
		return nil, err
	}
	return json.Marshal(m)
}