code: private void flushBuffer() throws IOException {
      if (this.dirty_) {
        if (this.diskPos_ != this.lo_) {
          super.seek(this.lo_);
        }
        int len = (int) (this.curr_ - this.lo_);
        super.write(this.buff_, 0, len);
        this.diskPos_ = this.curr_;
        this.dirty_ = false;
      }
    }
docs: /* Flush any dirty bytes in the buffer to disk.