// variables or the tensor is a constant this is safe, as future writes will
  // trigger copies).
  OP_REQUIRES_OK(context, LookupOrCreateResource<Var>(
                              context, HandleFromInput(context, 0), &variable,
                              [this, &value](Var** ptr) {
                                *ptr = new Var(dtype_);
                                *(*ptr)->tensor() = value;

  auto* cc_ctx = reinterpret_cast<::tensorflow::OpKernelContext*>(ctx);
  *maybe_resource = nullptr;
  if (cc_ctx->input_dtype(input) == tensorflow::DT_RESOURCE) {
    if (LookupResource(cc_ctx, HandleFromInput(cc_ctx, input), maybe_resource)
            .ok()) {
      return (*maybe_resource)->mu();
    } else {
      cc_ctx->CtxFailureWithWarning(
          tensorflow::errors::Internal("Invalid variable reference."));

    TF_OpKernelContext* ctx, int i, TF_Buffer* serialized_resource_handle_proto,
    TF_Status* status) {
  auto* cc_ctx = reinterpret_cast<::tensorflow::OpKernelContext*>(ctx);
  const tensorflow::ResourceHandle& handle = HandleFromInput(cc_ctx, i);
  tensorflow::ResourceHandleProto handle_proto;
  handle.AsProto(&handle_proto);
  auto cc_status = tensorflow::MessageToBuffer(
      handle_proto, serialized_resource_handle_proto);

    if (actual_input_index < 0 || actual_input_index >= ctx->num_inputs()) {
      return errors::Internal("Invalid input index for variable write.");
    }

    const ResourceHandle handle = HandleFromInput(ctx, actual_input_index);
    TF_ASSIGN_OR_RETURN(Var * variable,
                        GetOrCreateResourceVar(ctx, handle, write));
    out.emplace_back(actual_input_index, handle.name(), variable,