'L{mutuallyExclusiveArguments} raises a L{TypeError}n if its
decoratee is passed a pair of mutually exclusive arguments.'

def test_mutualExclusionExcludesByKeyword(self):

    @_mutuallyExclusiveArguments([['a', 'b']])
    def func(a=3, b=4):
        return (a + b)
    self.assertRaises(TypeError, func, a=3, b=4)
