Method subscribe

include/behaviortree_cpp/utils/signal.h:37–42

  }

  Subscriber subscribe(CallableFunction func)
  {
    Subscriber sub = std::make_shared<CallableFunction>(std::move(func));
    subscribers_.emplace_back(sub);
    return sub;
  }

private:
  std::vector<std::weak_ptr<CallableFunction>> subscribers_;