gistfile1.py

    def _do_highlight(self, content, text, tag='em'):
        """
        Highlight `text` in `content` with html `tag`.
        
        This method assumes that the input text (`content`) does not contain
        any special formatting.  That is, it does not contain any html tags
        or similar markup that could be screwed up by the highlighting.
        
        Required arguments:
            `content` -- Content to search for instances of `text`
            `text` -- The text to be highlighted
        """
        for term in [term.replace('*', '') for term in text.split()]:
            term_re = re.compile(re.escape(term), re.IGNORECASE)
            content = term_re.sub('<%s>%s</%s>' % (tag, term, tag), content)
        return content