code: def update_record(self, zeroconf, now, record):
          
          if record.type == _TYPE_PTR and record.name == self.type:
              expired = record.is_expired(now)
              try:
                  oldrecord = self.services[record.alias.lower()]
                  if not expired:
                      oldrecord.reset_ttl(record)
                  else:
                      del(self.services[record.alias.lower()])
                      callback = lambda x: self.listener.remove_service(x,
                              self.type, record.alias)
                      self.list.append(callback)
                      return
              except:
                  if not expired:
                      self.services[record.alias.lower()] = record
                      callback = lambda x: self.listener.add_service(x,
                              self.type, record.alias)
                      self.list.append(callback)
  
              expires = record.get_expiration_time(75)
              if expires < self.next_time:
                  self.next_time = expires
docs: Callback invoked by Zeroconf when new information arrives.
  
          Updates information required by browser in the Zeroconf cache.