Another cool mini-project: advance a range within n steps from its end

[Andrei Alexandrescu via Digitalmars-d]

Like "tail" in Unix. Given a range R r and a number size_t n, return a 
TakeExactly!R that's r at no more than n steps from its end:

TakeExactly!R advanceWithin(R)(R r, size_t n)
if (isForwardRange!R);
Invariant:

assert(r.advanceWithin(n).length <= n);

Implementation would send a scout range ahead, etc.

I didn't file an issue for it, but it's a great function to have.


Takers?

Andrei