'Require that an owner name (and optionally an rdata type) does
not exist as a prerequisite to the execution of the update.'

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)
