Macro awint_internals::for_each_mut

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

f(x) is run on every digit from first to last.