You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: example_test.go
    path of file: ./repos/msgpack
    
    the code of the file until where you have to start completion: package msgpack_test

import (
	"bytes"
	"fmt"

	"github.com/vmihailenco/msgpack/v5"
)

func ExampleMarshal() {
	type Item struct {
		Foo string
	}

	b, err := msgpack.Marshal(&Item{Foo: "bar"})
	if err != nil {
		panic(err)
	}

	var item Item
	err = msgpack.Unmarshal(b, &item)
	if err != nil {
		panic(err)
	}
	fmt.Println(item.Foo)
	// Output: bar
}

func ExampleMarshal_mapStringInterface() {
	in := map[string]interface{}{"foo": 1, "hello": "world"}
	b, err := msgpack.Marshal(in)
	if err != nil {
		panic(err)
	}

	var out map[string]interface{}
	err = msgpack.Unmarshal(b, &out)
	if err != nil {
		panic(err)
	}

	fmt.Println("foo =", out["foo"])
	fmt.Println("hello =", out["hello"])

	// Outpu
    
func ExampleDecoder_SetMapDecoder() {
	buf := new(bytes.Buffer)

	enc := msgpack.NewEncoder(buf)
	in := map[string]string{"hello": "world"}
	err := enc.Encode(in)
	if err != nil {
		panic(err)
	}

	dec := msgpack.NewDecoder(buf)

	// Causes decoder to produce map[string]string instead of map[string]interface{}.
	dec.SetMapDecoder(func(d *msgpack.Decoder) (interface{}, error) {
		n, err := d.DecodeMapLen()
		if err != nil {
			return nil, err
		}

		m := make(map[string]string, n)
		for i := 0; i < n; i++ {
			mk, err := d.DecodeString()
			if err != nil {
				return nil, err
			}

			mv, err := d.DecodeString()
			if err != nil {
				return nil, err
			}

			m[mk] = mv
		}
		return m, nil
	})

	out, err := dec.DecodeInterface()
	if err != nil {
		panic(err)
	}
	fmt.Printf("%#v", out)
	// Output: map[string]string{"hello":"world"}
}