code: func (w *wrappedWAL) Save(st raftpb.HardState, ents []raftpb.Entry) error {
  	var writeEnts []raftpb.Entry
  	for _, ent := range ents {
  		data, err := encryption.Encrypt(ent.Data, w.encrypter)
  		if err != nil {
  			return err
  		}
  		writeEnts = append(writeEnts, raftpb.Entry{
  			Index: ent.Index,
  			Term:  ent.Term,
  			Type:  ent.Type,
  			Data:  data,
  		})
  	}
  
  	return w.WAL.Save(st, writeEnts)
  }
docs: // Save encrypts the entry data (if an encrypter is exists) before passing it onto the
  // wrapped wal.WAL's Save function.