DB<114> $in_str = 'aa<c><d>r';
 => "aa<c><d>r"

  DB<115> if ($in_str =~ /aa((<[^>]*>)*)$/) {print "$1"}
 => ""

  DB<116> $in_str = 'aa<c><d>';
 => "aa<c><d>"

  DB<117> if ($in_str =~ /aa((<[^>]*>)*)$/) {print "$1"}
 => 1
<c><d>