sub rand2 {
    my $foo = shift;
    for (my $i = length($foo); --$i; ) {
        my $j = int rand ($i+1);
        (substr($foo, $i, 1), substr($foo, $j, 1)) = (substr($foo, $j, 1), substr($foo, $i, 1)) 
    }
    return $foo;
}