Macro awint_internals::binop_for_each_mut

macro_rules! binop_for_each_mut {
    ($lhs : ident, $rhs : ident, $x : ident, $y : ident, $f : block,
 $clear_unused_bits : expr) => { ... };
}

If lhs.bw() != rhs.bw(), this returns None, otherwise f(x, y) is run on every corresponding pair of digits from first to last.