I don't want to compare the contents of the range, but I'm
iterating a range and at some point I want to know if I have been
there before. Using RA I can just use indices.
If you meant comparing the actual range objects using "r ==
r.save", that doesn't hold either: If a is a "reference
semantic range", such as a class, then the saved range will be
different from the old range.
Note that in both cases, this has nothing to do with RA vs Frwd.
The classes could overload opEquals to return the correct thing.
(Note: Both of my ranges have the same type). But it'd guess they
are not required to.
