human
Here's a good function header given the following:
I wrote the below code

    def keep_alive(o):
        pass
    def test_runner():
        import _weakref
        global called
        called = 0
        a = IronPythonTest.Events()
        def foo():
            global called
            called += 1
        foo.abc = a
        a.InstanceTest += foo
        a.CallInstance()
        AreEqual(called, 1)
        ret_val = _weakref.ref(foo)
        keep_alive(foo)
        import gc
        for i in xrange(10):
            gc.collect()
        a.CallInstance()
        AreEqual(called, 2)
        return ret_val
    func_ref = test_runner()
    import gc
    for i in xrange(10):
        gc.collect()
    Assert((not hasattr(func_ref, 'abc')))
    AreEqual(func_ref(), None)
    AreEqual(called, 2)

What's a good function header?
assistant
#Here's a good function header.

@skip('silverlight')
def test_event_lifetime():