code: func (bt *Translator) Get(field string, id uint64) (val interface{}) {
  	bt.fmu.RLock()
  	if _, ok := bt.fields[field]; !ok {
  		panic(errors.Errorf("can't Get() with unknown field '%v'", field))
  	}
  	bt.fmu.RUnlock()
  	err := bt.Db.View(func(tx *bolt.Tx) error {
  		ib := tx.Bucket(idBucket)
  		fib := ib.Bucket([]byte(field))
  		idBytes := make([]byte, 8)
  		binary.BigEndian.PutUint64(idBytes, id)
  		val = fib.Get(idBytes)
  		return nil
  	})
  	if err != nil {
  		panic(err)
  	}
  	return val
  }
docs: // Get returns the previously mapped value to the monotonic id generated from
  // GetID. For BoltTranslator, val will always be a []byte.