[Issue 13936] groupBy must be redone

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=13936

--- Comment #34 from Andrei Alexandrescu <andrei at erdani.com> ---
reping @hstehoh jiust because I see him active in the forum and we need to get
this and aggregate() done before the next release. @hsteoh please let me know
if you want to work on this or I should. Thanks!

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