def visit(hook_event, *data)
      each { |subscriber|
        synchronize { hook_event.notify(subscriber, *data) }
      }
    end
def visit(hook_event, *data)
      each { |subscriber|
        synchronize { hook_event.notify(subscriber, *data) }
      }
    end
Visit subscribers and notify

 @param [HookEvent] hook_event
   the callback event to notify about

 @return [undefined]

 @api public