Doubt with parameter

I'm watching a video of python but I do not understand one thing.

I have the file utils.py

def code_generator(size=6, chars=string.ascii_lowercase + string.digits):
    return ''.join(random.choice(chars) for _ in range(size))

def create_shortcut(instance, size = 6):
    new_code = code_generator(size = size)
    Klass = instance.__class__
    qs_exists = Klass.objects.filter(shortcode=new_code).exists()
    if qs_exists:
        return create_shortcut(size = size)
    return new_code

Model.py file

def save(self, *args, **kargs):
   if self.shortcode is None or self.shortcode == "":
       self.shortcode = create_shortcut(self)
   super(KirrURL, self).save(*args, **kargs)

In the model.py file the create_shortcut(self) call is made, which means that the class itself is passed, and the size parameter, which is default 6, has not been entered.

However, here in utils.py:

 if qs_exists:
    return create_shortcut(size = size)

In the above passage would not it have to be return create_shortcut(instance, size = size) ? Why was not the instance parameter passed again?