def test_equal_2(self):
     self.assertEqual(basic_op('-', 15, 18), -3)
 def test_equal_4(self):
     self.assertEqual(basic_op('/', 49, 7), 7)
 def test_equal_1(self):
     self.assertEqual(basic_op('+', 4, 7), 11)
 def test_equal_3(self):
     self.assertEqual(basic_op('*', 5, 5), 25)