'L{mutuallyExclusiveArguments} does not interfere in its
decoratee\'s operation, either its receipt of arguments or its return
value.'

def test_mutualExclusionPrimeDirective(self):

    @_mutuallyExclusiveArguments([('a', 'b')])
    def func(x, y, a=3, b=4):
        return (((x + y) + a) + b)
    self.assertEqual(func(1, 2), 10)
    self.assertEqual(func(1, 2, 7), 14)
    self.assertEqual(func(1, 2, b=7), 13)
