code: func (s *Reporter) trackRequest(opType OpType, key []byte, endKey []byte) {
  	if !s.TrackTopRequests {
  		return
  	}
  	if len(key) == 0 {
  		return
  	}
  	// take just the first two parts, otherwise too many distinct requests
  	// can end up in the map
  	parts := bytes.Split(key, []byte{Separator})
  	if len(parts) > 3 {
  		parts = parts[:3]
  	}
  	rangeSuffix := teleport.TagFalse
  	if len(endKey) != 0 {
  		// Range denotes range queries in stat entry
  		rangeSuffix = teleport.TagTrue
  	}
  	counter, err := requests.GetMetricWithLabelValues(s.Component, string(bytes.Join(parts, []byte{Separator})), rangeSuffix)
  	if err != nil {
  		log.Warningf("Failed to get counter: %v", err)
  		return
  	}
  	counter.Inc()
  }
docs: // trackRequests tracks top requests, endKey is supplied for ranges