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: symmetric.go
    path of file: ./repos/k6/vendor/github.com/lestrrat-go/jwx/v2/jwk
    
    the code of the file until where you have to start completion: package jwk

import (
	"crypto"
	"fmt"

	"github.com/lestrrat-go/blackmagic"
	"github.com/lestrrat-go/jwx/v2/internal/base64"
)

func (k *symmetricKey) FromRaw(rawKe
    
func (k *symmetricKey) Thumbprint(hash crypto.Hash) ([]byte, error) {
	k.mu.RLock()
	defer k.mu.RUnlock()
	var octets []byte
	if err := k.Raw(&octets); err != nil {
		return nil, fmt.Errorf(`failed to materialize symmetric key: %w`, err)
	}

	h := hash.New()
	fmt.Fprint(h, `{"k":"`)
	fmt.Fprint(h, base64.EncodeToString(octets))
	fmt.Fprint(h, `","kty":"oct"}`)
	return h.Sum(nil), nil
}