wp-includes/Text/Diff.php:472 function &reverse() { $reverse = new Text_Diff_Op_change($this->final, $this->orig); return $reverse; }Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/Text/Diff.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.