Illuminate\Database\Eloquent\Builder::onDelete PHP Method

    public function onDelete(Closure $callback)
    {
        $this->onDelete = $callback;
    }

 /**
  * Register a replacement for the default delete function.
  *
  * @param \Closure $callback
  * @return void 
  * @static 
  */
 public static function onDelete($callback)
 {
     \Illuminate\Database\Eloquent\Builder::onDelete($callback);
 }