def METHOD_NAME(self):
    self.assertEqual(simple_eval("-2"), -2)
    self.assertEqual(simple_eval("1 + 1"), 2)
    self.assertEqual(simple_eval("a - 2", {"a": 1}), -1)
    with self.assertRaises(ValueError):
        simple_eval("2 * 3")
    with self.assertRaises(ValueError):
        simple_eval("2 ** 3")