code: def ns_whois(self, nameservers, limit=DEFAULT_LIMIT, offset=DEFAULT_OFFSET, sort_field=DEFAULT_SORT):
          '''Gets the domains that have been registered with a nameserver or
          nameservers'''
          if not isinstance(nameservers, list):
              uri = self._uris["whois_ns"].format(nameservers)
              params = {'limit': limit, 'offset': offset, 'sortField': sort_field}
          else:
              uri = self._uris["whois_ns"].format('')
              params = {'emailList' : ','.join(nameservers), 'limit': limit, 'offset': offset, 'sortField': sort_field}
  
          resp_json = self.get_parse(uri, params=params)
          return resp_jsof ns_whois(self, nameservers, limit=DEFAULT_LIMIT, offset=DEFAULT_OFFSET, sort_field=DEFAULT_SORT):
          '''Gets the domains that have been registered with a nameserver or
          nameservers'''
          if not isinstance(nameservers, list):
              uri = self._uris["whois_ns"].format(nameservers)
              params = {'limit': limit, 'offset': offset, 'sortField': sort_field}
          else:
              uri = self._uris["whois_ns"].format('')
              params = {'emailList' : ','.join(nameservers), 'limit': limit, 'offset': offset, 'sortField': sort_field}
  
          resp_json = self.get_parse(uri, params=params)
          return resp_json
docs: Gets the domains that have been registered with a nameserver or
          nameservers