wp-includes/Text/Diff.php:179Gets the original set of lines.
array function getOriginal() { $lines = array(); foreach ($this->_edits as $edit) { if ($edit->orig) { array_splice($lines, count($lines), 0, $edit->orig); } } return $lines; }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.