human
I wrote the below code

    filename = os.path.join('NeXML/', source)
    if (source in tree_counts):
        count = tree_counts[source]
    else:
        count = 1
    def test_parse(self):
        trees = list(bp._io.parse(filename, 'nexml'))
        self.assertEqual(len(trees), count)
    test_parse.__doc__ = ('Parse    the    phylogenies    in    %s.' % source)
    return test_parse

What's a good function header?

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

def _test_parse_factory(source):