unroll
Note: this item was deleted in
version 3.0.0
v. To repeat the body of a loop several times in succession.
This optimization technique reduces the number of times the
loop-termination test has to be executed. But it only works if
the number of iterations desired is a multiple of the number of
repetitions of the body. Something has to be done to take care
of any leftover iterations ---
such as Duff's device.
