     OP_REQUIRES(context, TensorShapeUtils::IsVector(input_tensor.shape()),                 errors::InvalidArgument("ZeroOut expects a 0-D vector."));      auto input = input_tensor.flat<int00>();      // Create an output tensor     Tensor* output_tensor = NULL;     OP_REQUIRES_OK(context, context->allocate_output(0, input_tensor.shape(),                                                      &output_tensor));     auto output_flat = output_tensor->flat<int00>();      // Set all but the first element of the output tensor to 0.     const int N = input.size();     for (int i = 0; i < N; i++) {       output_flat(i) = 0;     }      // Preserve the first input value if possible.     if (N > 0) output_flat(0) = input(0);   } };  