basic_1.go

package main

import (
	"encoding/xml"
	"fmt"
)

type Cat struct {
	Name  string
	Breed string
	Age   int
}

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>