Perl Style: Embrace && and || for Control and Values

Perl's && and || operators short circuit like C's, but return different values: they return the first thing that resolves them.

This is most often used with ||:

    ++$count{ $shell || "/bin/sh" };

    $a = $b || 'DEFAULT';

    $x ||= 'DEFAULT';

Sometimes it can be done with && also, usually providing the false value is '' not 0. (False tests in Perl return '' not 0!).
```
    $nulled_href = $href . ($add_nulls && "\0");
```