public IActionResult AddCity([FromBody] CityCreateOrUpdateModel cityCreateModel)
        {
            var citiesDataStore = CitiesDataStore.GetInstance();

            var  id   = citiesDataStore.Cities.Keys.Max() + 1;
            City city = cityCreateModel.ConverToCity(id);

            citiesDataStore.Cities.Add(city.Id, city);

            return(Created($"/api/cities/{id}" + city.Id, new CityGetModel(city)));
        }
        public IActionResult ReplaceCity(int id, [FromBody] CityCreateOrUpdateModel cityCreateOrUpdateModel)
        {
            var citiesDataStore = CitiesDataStore.GetInstance();

            if (citiesDataStore.Cities.ContainsKey(id))
            {
                citiesDataStore.Cities[id].Name        = cityCreateOrUpdateModel.Name;
                citiesDataStore.Cities[id].Description = cityCreateOrUpdateModel.Description;
                citiesDataStore.Cities[id].NumberOfPointsOfInterest = cityCreateOrUpdateModel.NumberOfPointsOfInterest;
                return(Ok(new CityGetModel(citiesDataStore.Cities[id])));
            }

            return(NotFound());
        }