def test_check_str(self):
types = [None, True, 1, "", "string", [], (), {}]
# pass: string
for element in [t for t in types if isinstance(t, str)]:
self.assertIsNone(PXML.check_str(element))
# fail: non-string
for element in [t for t in types if not isinstance(t, str)]:
with self.assertRaises(TypeError):
PXML.check_str(element)
