code: func (i *Iterator) Next() (key, value []byte) {
  	for {
  		if i.sliceCur >= len(i.m.entryStore.slices) {
  			return nil, nil
  		}
  		entrySlice := i.m.entryStore.slices[i.sliceCur]
  		if i.entryCur >= len(entrySlice) {
  			i.sliceCur++
  			i.entryCur = 0
  			continue
  		}
  		entry := entrySlice[i.entryCur]
  		key, value = i.m.dataStore.getEntryData(entry)
  		i.entryCur++
  		return
  	}
  }
docs: // Next returns the next key/value pair of the MVMap.
  // It returns (nil, nil) when there is no more entries to iterate.