A transform block consists of lines, where every 2 lines is a transform
The first line of each transform is a pattern, and the second is the
replacement.  These are passed to re.sub, like so:
re.sub(pattern, replacement, page_data)

Here is the set of transforms for the [[tbwiki.header]] page:

Ignore the trailbar

{{{transforms
class=trailbar.*
class=trailbar></td></tr>
}}}