private static void AddManyToManyObject()
        {
            var context = new SnowboardAppContext();
            var athlete = new Athlete {
                FirstName = "Torsten", LastName = "Horgmo", Age = 28, BirthCountry = "Norway",
            };
            var contest = context.Contests.Find(1);

            context.Add(athlete);
            context.Add(new AthleteContest {
                Athlete = athlete, Contest = contest
            });
            context.SaveChanges();
        }
        private static void AddSnowboardsToAthelte()
        {
            var context   = new SnowboardAppContext();
            var snowboard = new Snowboard {
                Brand = "Rome", Length = 150, Name = "SKS", AthelteId = 14
            };

            context.Add(snowboard);
            context.SaveChanges();

            var snowboard1 = new Snowboard {
                Brand = "Brädan1337", Length = 1337, Name = "ELIT", AthelteId = 14
            };

            context.Add(snowboard1);
            context.SaveChanges();
        }