code: func ExtractRawCertificateFromContext(ctx context.Context) []byte {
  	cert := ExtractCertificateFromContext(ctx)
  	if cert == nil {
  		return nil
  	}
  	return cert.Raw
  }
docs: // ExtractRawCertificateFromContext returns the raw TLS certificate (if applicable)
  // from the given context of a gRPC stream