[Issue 13595] Extend std.algorithm.groupBy to support non-equivalence relations

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=13595

--- Comment #11 from hsteoh at quickfur.ath.cx ---
P.S. the groupBy predicate can also be simplified to just: .groupBy!((w1, w2)
=> w1 == w2)

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