static void Main(string[] args)
        {
            var buEvaluation = new BasicUsersEvaluation
            {
                Id          = 1,
                User        = "******",
                Description = "Good city to visit",
                Grade       = 3
            };

            var puEvaluation = new PrimeUsersEvaluation
            {
                Id          = 2,
                User        = "******",
                Description = "Good city to visit",
                Grade       = 4
            };

            var service = new EvaluationService <CityEvaluation>();

            service.content.Evaluations.Add(buEvaluation);
            service.content.Evaluations.Add(puEvaluation);
            Console.WriteLine($"Type of evaluation: {service.GetTypeOfEvaluation()}");
            Console.WriteLine($"The final evaluation is {service.CalculateEvaluationAverage()}");
            Console.ReadKey();
        }