How does the `eat_exclude_types` filter work?

Your plugin is really great. I love how simple and clean the code is.

I had one question around line 42 — https://plugins.trac.wordpress.org/browser/easy-add-thumbnail/trunk/easy-add-thumbnail.php#L42

There’s a filter called eat_exclude_types:

$exclude_types     = array( '' );
$exclude_types     = apply_filters( 'eat_exclude_types', $exclude_types );

I understand why you’re excluding some post types. But the eat_exclude_types filter doesn’t seem to be defined anywhere and just wasn’t sure if that’s actually doing anything or just old code leftover or what. I tried searching around to understand it a bit better, but had a hard time finding info for when a filter fn is undefined.

Thanks!

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