code: @Override
    public void write(byte[] b, int offset, int len) throws IOException {
      long startTime = System.nanoTime();
      out.write(b, offset, len);
      statistics.incrementBytesWritten(len);
      long duration = System.nanoTime() - startTime;
      ghfs.increment(GoogleHadoopFileSystemBase.Counter.WRITE);
      ghfs.increment(GoogleHadoopFileSystemBase.Counter.WRITE_TIME, duration);
    }
docs: Writes to this output stream 'len' bytes of the specified buffer starting at the given offset.