For solving this task we will use the nlohmann/json library again. Instead of writing from_json() functions, as was mentioned in the solution to the previous problem, we will take a more explicit approach. The content of a JSON file can be loaded into an nlohmann::json object using the overloaded operator>>. To access the object values, you should use the at() method rather than operator[], because the former throws an exception if the key does not exist (an exception that you can handle), while the latter exhibits undefined behavior. To retrieve an object value as a particular T object, use the get<T>() method. However, this requires the type T to be default constructible.
The deserialize() function shown ...
