[Issue 13041] std.range.transposed consumes sub-ranges

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=13041

--- Comment #3 from hsteoh at quickfur.ath.cx ---
I wonder if there's any possibility of implementing .save for a random-access
range, if the subranges are also random-access.

In this case, we wouldn't need to consume the subranges at all, but can simply
store a set of current indices to implement .transposed.

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