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

    fname = os.path.basename(source)
    def test_parse(self):
        trees = PhyloXMLIO.parse(source)
        self.assertEqual(len(list(trees)), count)
    test_parse.__doc__ = ('Parse    the    phylogenies    in    %s.' % fname)
    return test_parse

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

def _test_parse_factory(source, count):