code: def lookup_thread_id(self):
          
  
          query_string = 'in:title "%s" repo:%s/%s' % (
              self.topic, self.owner, self.realm)
          cache_key = (self.owner, self.realm, self.topic)
          result = self.lookup_cache_key(cache_key)
          if result is not None:
              my_req = self.raw_pull(result)
              if my_req.status_code != 200:
                  result = None  # Cached item was no good
              elif my_req.json()['title'] != self.topic:
                  logging.debug('Title must have changed; ignore cache')
                  result = None
              else:
                  logging.debug('Using cached thread id %s for %s', str(result),
                                str(cache_key))
                  return result
          data, dummy_hdr = self.raw_search(self.user, self.token, query_string)
  
          if data['total_count'] == 1:   # unique match
              if data['items'][0]['title'] == self.topic:
                  result = data['items'][0]['number']
              else:
                  result = None
          elif data['total_count'] > 1:  # multiple matches since github doesn't
              searched_data = [          # have unique search we must filter
                  item for item in data['items'] if item['title'] == self.topic]
              if not searched_data:  # no matches
                  return None
              elif len(searched_data) > 1:
                  raise yap_exceptions.UnableToFindUniqueTopic(
                      self.topic, data['total_count'], '')
              else:
                  assert len(searched_data) == 1, (
                      'Confused searching for topic "%s"' % str(self.topic))
                  result = searched_data[0]['number']
          else:
              result = None
          self.update_cache_key(cache_key, result)
  
          return result
docs: Lookup thread id as required by CommentThread.lookup_thread_id.
  
          This implementation will query GitHub with the required parameters
          to try and find the topic for the owner, realm, topic, etc., specified
          in init.