docs: def _nextPage(self, offset):
          """Retrieves the next set of results from the service."""
          self.logger.debug("Iterator crecord=%s" % str(self.crecord))
  
          params = {
              'q': self.q,
              'rows': '0',
              'facet': 'true',
              'facet.field': self.field,
              'facet.limit': str(self.pagesize),
              'facet.offset': str(offset),
              'facet.zeros': 'false',
              'wt': 'python',
          }
          if self.fq is not None:
              params['fq'] = self.fq
          request = urllib.parse.urlencode(params, doseq=True)
          rsp = self.client.doPost(
              self.client.solrBase + '', request, self.client.formheaders
          )
          data = eval(rsp.read())
          try:
              self.res = data['facet_counts']['facet_fields'][self.field]
              self.logger.debug(self.res)
          except Exception:
              self.res = []
          self.index = 0