public HouseEntity Add(HouseEntity toAdd)
 {
     int newId = !GetAll().Any() ? 1 : GetAll().Max(x => x.Id) + 1;
     toAdd.Id = newId;
     _houses.Add(newId, toAdd);
     return toAdd;
 }
 public HouseDto MapToDto(HouseEntity houseEntity)
 {
     return new HouseDto()
     {
         Id = houseEntity.Id,
         ZipCode = houseEntity.ZipCode,
         City = houseEntity.City,
         Street = houseEntity.Street
     };
 }
        public HouseEntity Update(HouseEntity toUpdate)
        {
            HouseEntity single = GetSingle(toUpdate.Id);

            if (single == null)
            {
                return null;
            }

            _houses[single.Id] = toUpdate;
            return toUpdate;
        }