Stripe and tokens

I'm playing around abit with Stripe, and hit something i dont totally understand, I'm currently saveing the users card information, so i can charge it later, and sign it up for subscriptions, and im doing that like this:

    public function store(Request $request)
    {
        $input = $request->all();
       
        $user = User::findorFail(5);
        
        $customer = $user->createAsStripeCustomer(Input::get('stripeToken'));

     
    }

And when i want to charge the person it looks like this:

    public function pay(Request $request)
    {
               
         $user = User::findorFail(5);
        
        $user->charge(100000, [
         "currency" => 'dkk',
          "customer" => $user->stripe_id
        ]);
             
    }

Theese two work just as i want it too, even though i dont pass a token to the charge, as in the docs. But when i use the newSubscription I'm doing it like this:

    public function weekly(Request $request)
    {
          
        $user = User::findorFail(3);
        $token = "";
        $user->newSubscription('weekly','weekly')->create($token, [
         "currency" => 'dkk'
        ]);
         
    }

Here is my problem i dont understand which token it needs, currently i just use $token = ""; And that makes it work, if i dont have a variable it gives me an error. But what exactly happends here

 $user->newSubscription('weekly','weekly')->create($token, [
         "currency" => 'dkk'
        ]);

since it works with an empty variable?