wp-admin/includes/class-walker-nav-menu-checklist.php:53Ends the list of after the elements are added.
$outputstring$depthintoptional0$argsstdClassoptionalnull public function end_lvl( &$output, $depth = 0, $args = null ) { $indent = str_repeat( "\t", $depth ); $output .= "\n$indent</ul>"; }Introduced in 3.0.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-admin/includes/class-walker-nav-menu-checklist.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.