wp-includes/class-wp-theme.php:645Method to implement ArrayAccess for keys formerly returned by get_themes()
$offsetmixed #[ReturnTypeWillChange] public function offsetUnset( $offset ) {}Introduced in 3.4.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wp-theme.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.