docs: def garbage_collection(time_limit=YEAR/12.0):
      """
      Collect and remove all :class:`.RequestInfo` objects older than
      `time_limit` (in seconds).
  
      Args:
          time_limit (float, default YEAR / 2): Collect objects older than
              this limit.
      """
      expired_request_infos = (
          ri for ri in DATABASE.values()
          if ri.creation_ts + time_limit <= time.time()
      )
  
      for ri in expired_request_infos:
          del DATABASE[ri.url]