code: def make_post_unpack_alert(streamer):
      
      the_struct = ("version:L relayUntil:Q expiration:Q id:L cancel:L setCancel:[L] minVer:L "
                    "maxVer:L setSubVer:[S] priority:L comment:S statusBar:S reserved:S")
  
      alert_submessage_parser = _make_parser(streamer, the_struct)
  
      def post_unpack_alert(d, f):
          d1 = alert_submessage_parser(io.BytesIO(d["payload"]))
          d["alert_info"] = d1
          return d
      return post_unpack_alert
docs: Post-processor to "alert" message, to add an "alert_info" dictionary of parsed
      alert information.