Method check

Lib/test/test_xml_etree.py:2232–2236

(elem)

        # marshaller gives obscure errors for non-string values

        def check(elem):
            with self.assertRaises(TypeError) as cm:
                serialize(elem)
            self.assertEqual(str(cm.exception),
                    'cannot serialize 123 (type int)')

        elem = ET.Element(123)
        check(elem) # tag