human
I wrote the below code

    class IFilesystemSnapshotsTests(AsyncTestCase, ):
        '\n                                Tests    for    :class:`IFilesystemSnapshots`    implementors.\n\n                                These    are    functional    tests    if    run    against    real    filesystems.\n                                '
        def test_interface(self):
            '\n                                                The    tested    object    provides    :class:`IFilesystemSnapshots`.\n                                                '
            fs_snapshots = fixture(self)
            self.assertTrue(verifyObject(IFilesystemSnapshots, fs_snapshots))
        def test_created(self):
            '\n                                                Snapshots    created    with    ``create()``    are    listed    in    that    order    in\n                                                ``list()``.\n                                                '
            fs_snapshots = fixture(self)
            d = fs_snapshots.create('first')
            d.addCallback((lambda _: fs_snapshots.create('another')))
            d.addCallback((lambda _: fs_snapshots.list()))
            d.addCallback(self.assertEqual, ['first', 'another'])
            return d
    return IFilesystemSnapshotsTests

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

def make_ifilesystemsnapshots_tests(fixture):