  explicit ToTFRecordOp(OpKernelConstruction* ctx)
      : AsyncOpKernel(ctx),
        background_worker_(ctx->env(), "tf_data_to_tf_record") {}
  explicit ToTFRecordOp(OpKernelConstruction* ctx)
      : AsyncOpKernel(ctx),
        background_worker_(ctx->env(), "tf_data_to_tf_record") {}