How to use the @tanker/stream-base.Transform function in @tanker/stream-base

_initializeStreams() {
    this._resizerStream = new ResizerStream(this._maxClearChunkSize);

    this._encryptorStream = new Transform({
      // buffering input bytes until clear chunk size is reached
      writableHighWaterMark: this._maxClearChunkSize,
      writableObjectMode: false,
      // buffering output bytes until encrypted chunk size is reached
      readableHighWaterMark: this._maxEncryptedChunkSize,
      readableObjectMode: false,

      transform: (clearData, encoding, done) => {
        try {
          const encryptedChunk = this._encryptChunk(clearData);
          this._encryptorStream.push(encryptedChunk);
        } catch (err) {
          return done(err);
        }
        done();
      },

let resourceId;

    try {
      ({ encryptedChunkSize, resourceId } = encryptionV4.unserialize(headOfEncryptedData));
    } catch (e) {
      throw new InvalidArgument('encryptedData', e, headOfEncryptedData);
    }

    const key = await this._mapper.findKey(resourceId);

    this._state.maxEncryptedChunkSize = encryptedChunkSize;
    this._resizerStream = new ResizerStream(encryptedChunkSize);

    const b64ResourceId = utils.toBase64(resourceId);

    this._decryptionStream = new Transform({
      // buffering input bytes until encrypted chunk size is reached
      writableHighWaterMark: encryptedChunkSize,
      writableObjectMode: false,
      // buffering output bytes until clear chunk size is reached
      readableHighWaterMark: encryptedChunkSize - encryptionV4.overhead,
      readableObjectMode: false,

      transform: (encryptedChunk, encoding, done) => {
        try {
          const clearData = encryptionV4.decrypt(key, this._state.index, encryptionV4.unserialize(encryptedChunk));
          this._decryptionStream.push(clearData);
        } catch (error) {
          return done(new DecryptionFailed({ error, b64ResourceId }));
        }
        this._state.lastEncryptedChunkSize = encryptedChunk.length;
        this._state.index += 1; // safe as long as index < 2^53