code: public void write(byte []buffer, int offset, int length, boolean isEnd)
      throws IOException
    {
      _crc = Crc64.generate(_crc, buffer, offset, length);
      
      _next.write(buffer, offset, length, isEnd);
    }
docs: Writes a buffer to the underlying stream.
  
  @param buffer the byte array to write.
  @param offset the offset into the byte array.
  @param length the number of bytes to write.
  @param isEnd true when the write is flushing a close.