[Issue 17742] std.range.transposed does not have opIndex

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=17742

--- Comment #2 from Vladimir Panteleev <dlang-bugzilla at thecybershadow.net> ---
Ouch. I didn't realize transposed works with jagged arrays.

Considering this issue and that transposed doesn't work with static arrays
(because they're not ranges), maybe a separate function would be better, which
is closer to the matrix operation (in supporting indexing and static arrays).

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