code: def _get_matching_dns_entry_ids(self, identifier=None, rtype=None,
                                      name=None, content=None):
          
          record_ids = []
          if not identifier:
              records = self._list_records(rtype, name, content)
              record_ids = [record['id'] for record in records]
          else:
              record_ids.append(identifier)
          return record_ids
docs: Return a list of DNS entries that match the given criteria.