// A sequence of thread wrappers, one per device, for executing operations in
  // parallel.
  //
  // Conceptually this is a thread pool with one thread per device. It requires
  // less synchronization than a thread pool would for this task, since Execute
  // acquires each thread in order (and so only one Execute will schedule
  // blocking collective operations at a time), and avoids some dynamic

typedef struct TFE_MonitoringBoolGaugeCell TFE_MonitoringBoolGaugeCell;
TF_CAPI_EXPORT extern void TFE_MonitoringBoolGaugeCellSet(
    TFE_MonitoringBoolGaugeCell* cell, bool value);
TF_CAPI_EXPORT extern bool TFE_MonitoringBoolGaugeCellValue(
    TFE_MonitoringBoolGaugeCell* cell);

// APIs for Bool Gauge without label.
typedef struct TFE_MonitoringBoolGauge0 TFE_MonitoringBoolGauge0;
TF_CAPI_EXPORT extern TFE_MonitoringBoolGauge0* TFE_MonitoringNewBoolGauge0(

  // with key `key` existed after the call.
  bool Delete(const std::string& key) {
    absl::MutexLock lock(&mu_);
    return DeleteLocked(key);
  }

  /// Look up the entry with key `key` and copy it to `value` if found. Returns
  /// true if an entry was found for `key`, and its timestamp is not more than
  /// max_age_ seconds in the past.
  bool Lookup(const std::string& key, T* value) {
    if (max_age_ == 0) {

  // Following two methods are used to support custom device.
  // Return true if the inputs contain custom device tensor handle. It means
  // that the argument need to be handled by a custom device.
  virtual bool HasCustomDeviceInput() const = 0;

  virtual const tensorflow::OpDef* OpDef() const = 0;

  virtual Status InputLength(const char* input_name, int* length) = 0;

// be included in the output properties.
TF_CAPI_EXPORT extern void TF_InferStatically(
    TF_GraphProperties* graph_properties, TF_Bool assume_valid_feeds,
    TF_Bool aggressive_shape_inference, TF_Bool include_input_tensor_values,
    TF_Bool include_output_tensor_values, TF_Status* s);

// Get the size of input OpInfo::TensorProperties given node name.
TF_CAPI_EXPORT extern void TF_GetInputPropertiesListSize(

  // We should specify openmode each time we call TempFile.
  TempFile(const std::string& temp_file_name, std::ios::openmode mode);
  TempFile(TempFile&& rhs);
  ~TempFile() override;
  const std::string getName() const;
  bool truncate();

 private:
  const std::string name_;
};

 */
Status CalcNumericalGrad(AbstractContext* ctx, Model forward,
                         absl::Span<AbstractTensorHandle* const> inputs,
                         int input_index, bool use_function,
                         AbstractTensorHandle** numerical_grad);

}  // namespace gradients
}  // namespace tensorflow

  GCSFile(google::cloud::storage::Client&& gcs_client, bool compose,
          uint64_t block_size, size_t max_bytes, uint64_t max_staleness,
          uint64_t stat_cache_max_age, size_t stat_cache_max_entries);
} GCSFile;

// This function is used to initialize a filesystem without the need of setting
// manually environement variables.
void InitTest(TF_Filesystem* filesystem, bool compose, uint64_t block_size,

// Return a tensor handle containing a int scalar
TFE_TensorHandle* TestScalarTensorHandle(TFE_Context* ctx, int value);

// Return a tensor handle containing a bool scalar
TFE_TensorHandle* TestScalarTensorHandle(TFE_Context* ctx, bool value);

// Return a tensor handle containing a tstring scalar
TFE_TensorHandle* TestScalarTensorHandle(TFE_Context* ctx,

// and false is returned.
//
// Ownership of the items retrieved with this function remains with the library.
// Item points are invalidated after a call to TF_StringStreamDone.
TF_CAPI_EXPORT extern bool TF_StringStreamNext(TF_StringStream* list,
                                               const char** result);

// Frees the resources associated with given string list. All pointers returned