How to use the creoleparser.core.bldr function in Creoleparser

def _build(self, mo, element_store, environ):
        try:
            abbr, title = mo.group(1).split(":", 1)
        except ValueError:
            abbr = mo.group(1)
            title = None
        return creoleparser.core.bldr.tag.__getattr__('abbr')(
            creoleparser.core.fragmentize(abbr,
                                          self.child_elements,
                                          element_store, environ), title=title)

attrs = {}
    if isinstance(act, Activity):
        due = act.due_date
        if due:
            iso8601 = local_tz.localize(due).isoformat()
            text = act.due_date.strftime(dateformat)
            attrs['title'] = iso8601
        else:
            text = u'["%s" has no due date specified]' % (act.name)
            attrs['class'] = 'empty'
    else:
        # error
        text = act
        attrs['class'] = 'empty'

    return creoleparser.core.bldr.tag.__getattr__('span')(text, **attrs)