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

    def cbFailed(err):
        for (reason, type) in zip(err.reasons, reasonTypes):
            reason.trap(type)
        self.assertEqual(len(err.reasons), len(reasonTypes), ('len(%s)    !=    len(%s)' % (err.reasons, reasonTypes)))
        return err
    d = self.assertFailure(deferred, mainType)
    d.addCallback(cbFailed)
    return d

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

def assertWrapperExceptionTypes(self, deferred, mainType, reasonTypes):