docs: def pick_frequency_line(self, filename, frequency, cumulativefield='cumulative_frequency'):
          '''Given a numeric frequency, pick a line from a csv with a cumulative frequency field'''
          if resource_exists('censusname', filename):
              with closing(resource_stream('censusname', filename)) as b:
                  g = codecs.iterdecode(b, 'ascii')
                  return self._pick_frequency_line(g, frequency, cumulativefield)
          else:
              with open(filename, encoding='ascii') as g:
                  return self._pick_frequency_line(g, frequency, cumulativefield)