sub t1 {
    my $v = 'last expression';
    my $x = 'last assignment';
    unless ( $v ) {}
}
sub t2 {
    my $x = 'last assignment';
    unless ( 'last expression' ) {}
}
printf "t1 returns [%s]\n", t1();
printf "t2 returns [%s]\n", t2();
__END__
t1 returns [last expression]
t2 returns []