human
Solve the following python programming problem given the following code:
@ skipIfDBFeature ('can_defer_constraint_checks') 
def test_cannot_defer_constraint_checks(self) : 
    u = User.objects.create (avatar = Avatar.objects.create ()) 
    calls = [] 
    def noop(* args, **kwargs) : 
        calls.append ('') 
models.signals.post_delete.connect (noop, sender = User) 
    a = Avatar.objects.get (pk = a.avatar_id) 
    self.assertNumQueries (4, a.delete) 
    self.assertFalse (User.objects.exists ()) 
    self.assertFalse (Avatar.objects.exists ()) 
    self.assertEqual (len (calls), 1) 
    models.signals.post_delete.disconnect (noop, sender = User) 

    
    

    Fix the buggy line: a = Avatar.objects.get (pk = a.avatar_id)
assistant
#Here is Python program to fix the buggy line: a = Avatar.

a = Avatar.objects.get (pk = u.avatar_id)