throw IndexOutOfBoundsException()
    }
    var mutablePos = pos
    var mutableByteCount = byteCount

    while (mutableByteCount > 0L) {
      val bytesWritten = fileChannel.transferFrom(source, mutablePos, mutableByteCount)
      mutablePos += bytesWritten
      mutableByteCount -= bytesWritten
    }
  }

  /**
   * Copy [byteCount] bytes from the file at [pos] into `sink`. It is the

        URL website = new URL(urlString);
        ReadableByteChannel rbc;
        rbc = Channels.newChannel(website.openStream());
        FileOutputStream fos = new FileOutputStream(destination);
        fos.getChannel().transferFrom(rbc, 0, Long.MAX_VALUE);
        fos.close();
        rbc.close();
    }