find the key of groupby in linq C# :             var aaa = newList.GroupBy(o => o.Date).Select(o => new { o }).ToList();
//There is a error of `Key`

            var bbb = aaa.Select(o => o.Key).ToList();
does that mean the `Key` is only allowed for the original List after `GroupBy`. Is it possible to obtain the `Key` for any `Select` after `GroupBy`?(Surely, we can storge the `Key = o.Key` in the `Select` )

