elegant" but does not generalize to allow performing multiple iterations
in parallel, thus it doesn't seem relevant to LOOP.
>(sloop for i below 5
for u in-fringe '(1 (a . b) c)
collect (list i u))
((0 1) (1 A) (2 B) (3 C))
Most iterations can be done in parallel, only two loop-maps
are not currently allowed.
Bill