basic_2.go

package main

import (
	"encoding/xml"
	"fmt"
)

type Cat struct {
	Name  string `xml:"name"`
	Breed string `xml:"breed"`
	Age   int    `xml:"age"`
}

func main() {
	cat := Cat{
		Name:  "Olive",
		Breed: "Oriental Shorthair",
		Age:   1,
	}

	bytes, err := xml.MarshalIndent(cat, "", "  ")
	if err != nil {
		panic(err)
	}
	fmt.Println(string(bytes))
}

<Cat>
  <name>Olive</name>
  <breed>Oriental Shorthair</breed>
  <age>1</age>
</Cat>