absl::Span<AbstractTensorHandle* const> inputs,
                             std::vector<AbstractTensorHandle*>* params);

// A callable that takes tensor inputs and returns zero or more tensor outputs.
using Model = std::function<Status(AbstractContext*,
                                   absl::Span<AbstractTensorHandle* const>,
                                   absl::Span<AbstractTensorHandle*>)>;

Status ReluModel(AbstractContext* ctx,
                 absl::Span<AbstractTensorHandle* const> inputs,
                 absl::Span<AbstractTensorHandle*> outputs) {
  return ops::Relu(ctx, inputs[0], &outputs[0], "Relu");
}

Status SparseSoftmaxCrossEntropyWithLogitsModel(
    AbstractContext* ctx, absl::Span<AbstractTensorHandle* const> inputs,
    absl::Span<AbstractTensorHandle*> outputs) {
  AbstractTensorHandle* loss;

}
Status TapeOperation::SetAttrFunctionList(
    const char* attr_name, absl::Span<const AbstractOperation*> values) {
  return tensorflow::errors::Unimplemented(
      "SetAttrFunctionList has not been "
      "implemented yet.");
}
AbstractOperation* TapeOperation::GetBackingOperation() { return parent_op_; }
Status TapeOperation::Execute(absl::Span<AbstractTensorHandle*> retvals,
                              int* num_retvals) {

        "//tensorflow/c/eager:c_api_unified_internal",
        "//tensorflow/c/eager:tracing_utils",
        "//tensorflow/core:framework",
        "//tensorflow/core/platform:errors",
        "@com_google_absl//absl/types:span",
    ],
)

cc_library(
    name = "io_ops",
    srcs = [
        "io_ops.cc",
    ],
    hdrs = [
        "io_ops.h",
    ],
    visibility = [
        "//tensorflow:internal",
    ],

        "//tensorflow/c/eager:tfe_tensorhandle_internal",
        "//tensorflow/core:framework",
        "//tensorflow/core:lib",
        "@com_google_absl//absl/types:optional",
        "@com_google_absl//absl/types:span",
        "@com_google_absl//absl/types:variant",
    ],
)

tf_cc_test(
    name = "parallel_device_lib_test",
    srcs = ["parallel_device_lib_test.cc"],
    deps = [
        ":parallel_device_lib",

    for (auto output : forward_outputs_) {
      if (output) {
        output->Ref();
      }
    }
  }

  Status Compute(AbstractContext* ctx,
                 absl::Span<AbstractTensorHandle* const> grad_outputs,
                 absl::Span<AbstractTensorHandle*> grad_inputs) override {
    AbstractTensorHandle* upstream_grad = grad_outputs[0];
    AbstractTensorHandle* activations = forward_outputs_[0];

    // Calculate Grad

  virtual Status SetDeviceName(const char* name) = 0;

  virtual Status AddInput(AbstractTensorHandle* input) = 0;
  virtual Status AddInputList(
      absl::Span<AbstractTensorHandle* const> inputs) = 0;
  virtual Status Execute(absl::Span<AbstractTensorHandle*> retvals,
                         int* num_retvals) = 0;

  virtual Status SetAttrString(const char* attr_name, const char* data,

namespace internal {

void CompareNumericalAndAutodiffGradients(
    Model model, Model grad_model, AbstractContext* ctx,
    absl::Span<AbstractTensorHandle* const> inputs, bool use_function,
    double abs_error = 1e-2);

void CheckTensorValue(AbstractTensorHandle* t, absl::Span<const float> manuals,
                      absl::Span<const int64_t> dims, double abs_error = 1e-2);

Model BuildGradModel(Model forward, GradientRegistry registry);

}

std::vector<int64_t> MakeTensorIDList(
    absl::Span<AbstractTensorHandle* const> tensors) {
  std::vector<int64_t> ids(tensors.size());
  for (int i = 0; i < tensors.size(); i++) {
    ids[i] = ToId(tensors[i]);
  }
  return ids;
}

Status Tape::ComputeGradient(
    AbstractContext* ctx, absl::Span<AbstractTensorHandle* const> targets,
    absl::Span<AbstractTensorHandle* const> sources,

#include "tensorflow/c/experimental/gradients/not_differentiable.h"

namespace tensorflow {
namespace gradients {
Status NotDifferentiableGradientFunction::Compute(
    AbstractContext* ctx, absl::Span<AbstractTensorHandle* const> grad_outputs,
    absl::Span<AbstractTensorHandle*> grad_inputs) {
  for (int i = 0; i < grad_inputs.size(); i++) {
    grad_inputs[i] = nullptr;
  }
  return OkStatus();
}