code: func (rcv *PubSub) Stat(send helper.StatCallback) {
  	messagesReceived := atomic.LoadUint32(&rcv.messagesReceived)
  	send("messagesReceived", float64(messagesReceived))
  
  	metricsReceived := atomic.LoadUint32(&rcv.metricsReceived)
  	send("metricsReceived", float64(metricsReceived))
  
  	errors := atomic.LoadUint32(&rcv.errors)
  	send("errors", float64(errors))
  
  	if !rcv.statsAsCounters {
  		atomic.AddUint32(&rcv.messagesReceived, -messagesReceived)
  		atomic.AddUint32(&rcv.metricsReceived, -metricsReceived)
  		atomic.AddUint32(&rcv.errors, -errors)
  	}
  }
docs: // Stat sends pubsub receiver's internal stats to specified callback