code: def _make_default_header(self):
          
          td_max = 0
  
          for idx, tr in enumerate(self._tr_nodes):
              td_count = len(tr.contents.filter_tags(matches=ftag('td')))
              if td_count > td_max:
                  td_max = td_count
  
          self._log('creating default header (%d columns)' % td_max)
          return [ 'column%d' % n for n in range(0,td_max) ]
docs: Return a generic placeholder header based on the tables column count