for (auto accumulated : accumulated_gradients_) {
      vspace_.DeleteGradient(accumulated.second);
    }
  }

  // Tell the forward accumulator to watch tensor_id, with a Tensor tangent
  // vector `tangent` of matching shape and dtype. Tangents are the "vector" in
  // "Jacobian-vector product"; `Watch`ing a new Tensor and immediately calling
  // FetchJVP for it would return `tangent`.
  void Watch(int64_t tensor_id, Gradient* tangent);

  int (*get_children)(const TF_Filesystem* filesystem, const char* path,
                      char*** entries, TF_Status* status);

  /// Finds all entries matching the regular expression given by `glob`.
  ///
  /// Pattern must match the entire entry name, not just a substring.
  ///
  /// pattern: { term }
  /// term:
  ///   '*': matches any sequence of non-'/' characters