saveentities.swift

        let aDog = Dog(value: ["name": "Lulu", "age": 3])
        let anotherDog = Dog(value: ["name": "Nana", "age": 2])

        // Instead of using pre-existing dogs...
        let aPerson = Person(value: [123, "Jane", [aDog, anotherDog]])
        // ...we can create them inline
        let anotherPerson = Person(value: [456, "Jane", [["Buster", 5], ["Buddy", 6]]])

        repository.save(entities: [aPerson, anotherPerson], update: true) { result in
            switch result {
            case .success:
                print("Handle success here")
            case .failure:
                print("Handle failed here")
            }
        }