foreach (
   '**bold**',
   '``**bold**``',
   '**``bold``**',
   '**bold** test ** test',
   '``text`` test `` test',
) {
   print('in:  ', $_, $/, 'out: ');
   TOKENIZER: { ... }
   print($/, $/);
}

__END__
in:  **bold**
out: <b>bold</b>

in:  ``**bold**``
out: **bold**

in:  **``bold``**
out: <b>``bold``</b>

in:  **bold** test ** test
out: <b>bold</b> test ** test

in:  ``text`` test `` test
out: text test `` test