def get_dir_from_zipfile(zip_file, fallback=None):
    """Return the name of the root folder in a zip file.

    :param zip_file: a :class:`zipfile.ZipFile` instance.
    :param fallback: if `None`, the name of the zip file is used. This is
        returned if the zip file contains more than one top-level directory,
        or none at all.
    """
    fallback = fallback or zip_file.filename
    directories = [name for name in zip_file.namelist() if name.endswith("/")
                   and len(PurePath(name).parts) == 1]
    return fallback if len(directories) > 1 else directories[0]
def test_positional_args(self):
        # see also http://bugs.python.org/issue5042
        class W(Structure):
            _fields_ = [("a", c_int), ("b", c_int)]
        class X(W):
            _fields_ = [("c", c_int)]
        class Y(X):
            pass
        class Z(Y):
            _fields_ = [("d", c_int), ("e", c_int), ("f", c_int)]

        z = Z(1, 2, 3, 4, 5, 6)
        self.assertEqual((z.a, z.b, z.c, z.d, z.e, z.f),
                         (1, 2, 3, 4, 5, 6))
        z = Z(1)
        self.assertEqual((z.a, z.b, z.c, z.d, z.e, z.f),
                         (1, 0, 0, 0, 0, 0))
        self.assertRaises(TypeError, lambda: Z(1, 2, 3, 4, 5, 6, 7))