return $is_true ? 'is true!' : 'is false';

# is just a one line way of saying
if ($is_true) {
  return 'is true!';
}
else {
  return 'is false!';
}

##</code><code>##

$a = $is_true ? 'is true!' : $was_true ? 'was true' : 'was never true';

##</code><code>##

$some_boolean ? do_sub1() : do_sub2();