public async Task <User> Get(string key)
 {
     return(await Task.Run(() =>
     {
         UserMemoryMockModel item = GetItem(key);
         if (item is null)
         {
             throw new Exception($"Item not found in UserMemoryMockRepository for key {key}");
         }
         return UserMapper.Map(item);
     }));
 }
 public static User Map(UserMemoryMockModel userModel)
 {
     return(userModel is null ? null : new User(userModel.Nickname));
 }