public async Task <CityWalk[]> GetCityWalkAsync(string cityName, int totalTime, int?latitude = null, int?longitude = null, bool optimal = false, bool goInside = true, string tagLabels = null)
 {
     if (totalTime < 20 || totalTime > 360)
     {
         return(null);
     }
     return(await _travelInfoService.GetCityWalksAsync(cityName, totalTime, optimal, goInside, tagLabels, latitude, longitude));
 }