code: def absent(self, name, rdtype=None):
          
  
          if isinstance(name, (str, unicode)):
              name = dns.name.from_text(name, None)
          if rdtype is None:
              rrset = self.find_rrset(self.answer, name,
                                      dns.rdataclass.NONE, dns.rdatatype.ANY,
                                      dns.rdatatype.NONE, None,
                                      True, True)
          else:
              if isinstance(rdtype, (str, unicode)):
                  rdtype = dns.rdatatype.from_text(rdtype)
              rrset = self.find_rrset(self.answer, name,
                                      dns.rdataclass.NONE, rdtype,
                                      dns.rdatatype.NONE, None,
                                      True, True)
docs: Require that an owner name (and optionally an rdata type) does
          not exist as a prerequisite to the execution of the update.