// TF_ImportGraphDefOptionsAddInputMapping() that didn't appear in the GraphDef
// and weren't used as input to any node in the imported graph def. The number
// of fetched mappings is returned in `num_missing_unused_input_mappings`. The
// array of each mapping's source node name is returned in `src_names`, and the
// array of each mapping's source index is returned in `src_indexes`.
//

        VLOG(1) << "Tensor " << id << " is source";
        continue;
      }
      auto missing_it = state.op_missing_tensor.find(op_id);
      if (missing_it != state.op_missing_tensor.end()) {
        missing_it->second--;
        VLOG(1) << "Op " << op_id << " missing " << missing_it->second
                << " output gradients";
        if (missing_it->second == 0) {
          op_stack.insert(op_stack.begin(), op_id);
        }

struct TF_ImportGraphDefResults {
  std::vector<TF_Output> return_tensors;
  std::vector<TF_Operation*> return_nodes;
  std::vector<const char*> missing_unused_key_names;
  std::vector<int> missing_unused_key_indexes;

  // Backing memory for missing_unused_key_names values.
  std::vector<tensorflow::string> missing_unused_key_names_data;
};

struct TF_DeviceList {
  std::vector<tensorflow::DeviceAttributes> response;
};

  ///
  /// NOTE: The requirements specify that `TF_ALREADY_EXISTS` is not returned if
  /// directory exists. Similarly, `TF_NOT_FOUND` is not be returned, as the
  /// missing directory entry and all its descendants will be created by the
  /// plugin.
  ///
  /// DEFAULT IMPLEMENTATION: Creates directories one by one. Needs
  /// `path_exists`, `is_directory`, and `create_dir`.