if (undef($a) || undef($b)) { ... }

##</code><code>##

  if ($a = 1) { ... }

##</code><code>##

  my ($key, $value) = s/(\w+)=(.*)/$1: $2/;

##</code><code>##

  for my $splort (foo()) {
    do {
      chop($splort);
      last if $splort eq $root;
    } until (happy($splort));
    print "happy or root\n";
  }