void DeleteFile(const TF_Filesystem* filesystem, const char* path,
                TF_Status* status);
void Stat(const TF_Filesystem* filesystem, const char* path,
          TF_FileStatistics* stats, TF_Status* status);
void DeleteDir(const TF_Filesystem* filesystem, const char* path,
               TF_Status* status);
void CopyFile(const TF_Filesystem* filesystem, const char* src, const char* dst,
              TF_Status* status);

// Deletes the specified directory. Typical status codes are:
//  * TF_OK - successfully deleted the directory
//  * TF_FAILED_PRECONDITION - the directory is not empty
TF_CAPI_EXPORT extern void TF_DeleteDir(const char* dirname, TF_Status* status);

// Deletes the specified directory and all subdirectories and files underneath
// it. This is accomplished by traversing the directory tree rooted at dirname

  Status DeleteRecursively(const std::string& dirname, TransactionToken* token,
                           int64_t* undeleted_files,
                           int64_t* undeleted_dirs) override;
  Status DeleteDir(const std::string& dirname,
                   TransactionToken* token) override;
  Status RecursivelyCreateDir(const std::string& dirname,
                              TransactionToken* token) override;

                                                              TF_Status*);

// Creates a new TensorHandle from memory residing in the physical device
// device_name. Takes ownership of the memory, and will call deleter to release
// it after TF no longer needs it or in case of error.
//
// Custom devices must use TFE_NewCustomDeviceTensorHandle instead.
TF_CAPI_EXPORT extern TFE_TensorHandle* TFE_NewTensorHandleFromDeviceMemory(

                                      absl::MakeSpan(in_gradients));
      if (!persistent_) {
        trace.backward_function_deleter(trace.backward_function);
      }
      if (!s.ok()) {
        return s;
      }
    } else {
      if (!persistent_) {
        trace.backward_function_deleter(trace.backward_function);
      }
      for (Gradient* grad : out_gradients) {
        if (grad != nullptr) {