code: func (b *BasicAuth) StreamInterceptor(srv interface{}, stream grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
  	ctx := stream.Context()
  	if err := b.doAuth(ctx); err != nil {
  		return err
  	}
  	return handler(srv, stream)
  }
docs: // StreamInterceptor define stream interceptor