code: func ExtractCertificateHashFromContext(ctx context.Context) []byte {
  	rawCert := ExtractRawCertificateFromContext(ctx)
  	if len(rawCert) == 0 {
  		return nil
  	}
  	h := sha256.New()
  	h.Write(rawCert)
  	return h.Sum(nil)
  }
docs: // ExtractCertificateHashFromContext extracts the hash of the certificate from the given context.
  // If the certificate isn't present, nil is returned