my $blah = foo(1, 2);
sub foo {
    my ($var1, $var2) = @_;
    if ($var2 == 0) {
        return;
    }
    return $var1 + $var2;
}
# becomes
my $blah;
SOMEUNIQUELABEL:
{
    my ($var1, $var2) = (1, 2);
    if ($var2 == 0) {
        $blah = undef;
        last SOMEUNIQUELABEL;
    }
    $blah = $var1 + $var2;
    last SOMEUNIQUELABEL;
}