I don't think you need all of the explanation above. Just put a short summary under fsync:

```
Parameters
----------
fsync : bool (default False)
    call ``os.fsync()`` on the file handle to force writing to disk.
```

Then at the end you could add:

```
Notes
-----
Without ``fsync=True``, flushing may not guarantee that the OS writes to disk. With fsync, the operation will block until the OS claims the file has been written; however, other caching layers may still interfere.
```