docs: def size(self, destination):
          """
          Size of the queue for specified destination.
  
          @param destination: The queue destination (e.g. /queue/foo)
          @type destination: C{str}
  
          @return: The number of frames in specified queue.
          @rtype: C{int}
          """
          session = meta.Session()
          sel = select([func.count(model.frames_table.c.message_id)]).where(
              model.frames_table.c.destination == destination)
          result = session.execute(sel)
          first = result.fetchone()
          if not first:
              return 0
          else:
              return int(first[0])