code: def check_origin(self):
          
          if self.relativize:
              name = dns.name.empty
          else:
              name = self.origin
          if self.get_rdataset(name, dns.rdatatype.SOA) is None:
              raise NoSOA
          if self.get_rdataset(name, dns.rdatatype.NS) is None:
              raise NoNS
docs: Do some simple checking of the zone's origin.
  
          @raises dns.zone.NoSOA: there is no SOA RR
          @raises dns.zone.NoNS: there is no NS RRset
          @raises KeyError: there is no origin node