def test_len(self):
        """
        Test re-implementing len() for a custom type with @overload.
        """
        cfunc = jit(nopython=True)(len_usecase)
        self.assertPreciseEqual(cfunc(MyDummy()), 13)
        self.assertPreciseEqual(cfunc([4, 5]), 2)

        Test re-implementing len() for a custom type with @overload.
        
numba/tests/test_extending.py