[bugfix] Python2 does actual type checking on self arguments

python/dune/codegen/sumfact/accumulation.py

@@ -168,7 +168,7 @@ class AccumulationOutput(SumfactKernelInterfaceBase, ImmutableRecord):
             return ()
         else:
             from dune.codegen.sumfact.basis import SumfactBasisMixin
-            return SumfactBasisMixin.lfs_inames(None, get_leaf(self.trial_element, self.trial_element_index), self.restriction)
+            return SumfactBasisMixin.lfs_inames(SumfactBasisMixin(), get_leaf(self.trial_element, self.trial_element_index), self.restriction)
 
     def realize_input(self, inames, shape, vec_iname, vec_shape, buf, ftags):
         # The result of stage 2 has the correct quadrature permutation but no