code: def iterate_rdatasets(self, rdtype=dns.rdatatype.ANY,
                            covers=dns.rdatatype.NONE):
          
  
          if isinstance(rdtype, (str, unicode)):
              rdtype = dns.rdatatype.from_text(rdtype)
          if isinstance(covers, (str, unicode)):
              covers = dns.rdatatype.from_text(covers)
          for (name, node) in self.iteritems():
              for rds in node:
                  if rdtype == dns.rdatatype.ANY or \
                     (rds.rdtype == rdtype and rds.covers == covers):
                      yield (name, rds)
docs: Return a generator which yields (name, rdataset) tuples for
          all rdatasets in the zone which have the specified I{rdtype}
          and I{covers}.  If I{rdtype} is dns.rdatatype.ANY, the default,
          then all rdatasets will be matched.
  
          @param rdtype: int or string
          @type rdtype: int or string
          @param covers: the covered type (defaults to None)
          @type covers: int or string