human
Solve the following python programming problem given the following code:
@ skipUnlessDBFeature ('supports_3d_functions') 
def test_extent(self) : 
    '
        Testing the Extent3D aggregate for 3D models.
        ' 
    self._load_city_data () 
    ref_extent3d = ((- 123.305196), (- 41.315268), 14, 174.783117, 48.462611, 1433) 
    extent = City3D.objects.aggregate (Extent3D ('point')) ['point__extent3d'] 
    def check_extent3d(extent3d, tol = 6) : 
        for (ref_val, ext_val) in zip (ref_extent3d, extent3d) : 
            self.assertAlmostEqual (ref_val, ext_val, tol) 
check_extent3d (self) 
    self.assertIsNone (City3D.objects.none ().aggregate (Extent3D ('point')) ['point__extent3d']) 

    
    

    Fix the buggy line: check_extent3d (self)
assistant
#Here is Python code to fix the buggy line: check_extent3d (self)
.

check_extent3d (extent)