Support For Else Statement

[oovm]

for i in [1, 2, 3] if i % 2 == 0 {
    do_something(i)
}
else {
    do_something_else()
}

Equivalent to

let mut $iter = IntoIterator::into_iterator([1, 2, 3])
let mut $next = $iter.next()
let mut $no_run = true;
while $next.is_some() {
    let i = $next!;
    if i % 2 == 0 {
        $no_run = false;
        do_something(i);
    }
    $next = $iter.next()
}
if $no_run {
    do_something_else();
}