code: func (r *reporter) save() error {
  	//create a LevelDB Batch
  	batch := leveldb.Batch{}
  	//for each metric in the registry (which is independent)...
  	r.reg.Each(func(name string, i interface{}) {
  		metric, ok := i.(metrics.Counter)
  		if ok {
  			//assuming every metric here to be a Counter (separate registry)
  			//...create a snapshot...
  			ms := metric.Snapshot()
  			byteVal := make([]byte, 8)
  			binary.BigEndian.PutUint64(byteVal, uint64(ms.Count()))
  			//...and save the value to the DB
  			batch.Put([]byte(name), byteVal)
  		}
  	})
  	return r.db.Write(&batch, nil)
  }
docs: //send the metrics to the DB