code: def is_response(self, other):
          
          if other.flags & dns.flags.QR == 0 or \
             self.id != other.id or \
             dns.opcode.from_flags(self.flags) != \
             dns.opcode.from_flags(other.flags):
              return False
          if dns.rcode.from_flags(other.flags, other.ednsflags) != \
                 dns.rcode.NOERROR:
              return True
          if dns.opcode.is_update(self.flags):
              return True
          for n in self.question:
              if n not in other.question:
                  return False
          for n in other.question:
              if n not in self.question:
                  return False
          return True
docs: Is other a response to self?
          @rtype: bool