wp-includes/Text/Diff/Renderer.php:207$header function _startBlock($header) { return $header . "\n"; }Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/Text/Diff/Renderer.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.