virtual absl::Status RegisterFunction(AbstractFunction*) = 0;
  // Remove a function. 'func' argument is the name of a previously added
  // FunctionDef. The name is in fdef.signature.name.
  virtual absl::Status RemoveFunction(const string& func) = 0;

 private:
  const AbstractContextKind kind_;
};

namespace internal {
struct AbstractContextDeleter {
  void operator()(AbstractContext* p) const {
    if (p != nullptr) {

    return errors::Unimplemented(
        "Registering graph functions has not been implemented yet.");
  }

  absl::Status RemoveFunction(const string& func) override {
    return errors::Unimplemented(
        "GraphContext::RemoveFunction has not been implemented yet.");
  }
  // For LLVM style RTTI.
  static bool classof(const AbstractContext* ptr) {
    return ptr->getKind() == kGraph;
  }

}

void TF_GraphRemoveFunction(TF_Graph* g, const char* func_name,
                            TF_Status* status) {
  tensorflow::mutex_lock l(g->mu);
  status->status = g->graph.mutable_flib_def()->RemoveFunction(func_name);

  return result;
}

void TFE_ContextRemoveFunction(TFE_Context* ctx, const char* name,
                               TF_Status* status) {
  status->status = tensorflow::unwrap(ctx)->RemoveFunction(name);
}

unsigned char TFE_ContextHasFunction(TFE_Context* ctx, const char* name) {
  return tensorflow::unwrap(ctx)->FindFunctionDef(name) != nullptr;
}