Suggestion: Book level variables

[kovidgoyal]

It doesn't matter, you just need to change the search expression to match both the comment and the stuff after it. If the stuff after it is of undefined form, like tags, use a start and end comment, like this:

<!-- tags --><!-- end -->

with search expression

<!-- tags -->(.*?)<!--end -->

and function

def __call__(self, m):
   return '<!-- tags -->' + tags + '<!-- end -->'