private User ChangeCurrentTown(string username, string townName)
{
if (!townService.Exist(townName))
{
throw new ArgumentException($"Value {townName} not valid.{Environment.NewLine}" +
$"Town {townName} not found!");
}
User user = context.Users.First(u => u.Username == username);
user.CurrentTown.Name = townName;
context.SaveChanges();
return(user);
}