code: func NewMessageReceivedSizeStatsHandler(sub Subsystem, vec *prometheus.HistogramVec) *MessageReceivedSizeStatsHandler {
  	return &MessageReceivedSizeStatsHandler{
  		baseStatsHandler: baseStatsHandler{
  			subsystem: sub,
  			collector: vec,
  		},
  		vec: vec,
  	}
  }
docs: // NewMessageReceivedSizeStatsHandler ...