code: func (m *monitor) Describe(in chan<- *prometheus.Desc) {
  	// Gauge
  	m.connections.Describe(in)
  	m.requests.Describe(in)
  
  	// HistogramVec
  	m.requestDuration.Describe(in)
  
  	// CounterVec
  	m.requestsTotal.Describe(in)
  	m.messagesReceived.Describe(in)
  	m.messagesSend.Describe(in)
  	m.errors.Describe(in)
  }
docs: // Describe implements prometheus Collector interface.