code: def _list_records_in_zone(self, zone, rdtype=None, name=None, content=None):
          
          records = []
          rrsets = zone.iterate_rdatasets() if zone else []
          for rname, rdataset in rrsets:
              rtype = dns.rdatatype.to_text(rdataset.rdtype)
              if ((not rdtype or rdtype == rtype)
                      and (not name or name == rname.to_text())):
                  for rdata in rdataset:
                      rdata = rdata.to_text()
                      if not content or self._convert_content(rtype, content) == rdata:
                          raw_rdata = self._clean_TXT_record({'type': rtype,
                                                              'content': rdata})['content']
                          data = {
                              'type': rtype,
                              'name': rname.to_text(True),
                              'ttl': int(rdataset.ttl),
                              'content': raw_rdata,
                              'id': Provider._create_identifier(rtype, rname.to_text(), raw_rdata)
                          }
                          records.append(data)
          return records
docs: Iterates over all records of the zone and returns a list of records filtered
          by record type, name and content. The list is empty if no records found.