How to use the scandir.scandir_c function in scandir

def setUp(self):
                self.scandir_func = scandir.scandir_c
                self.has_file_attributes = True
                TestMixin.setUp(self)

help='version of scandir() to use, default "%default"')
    options, args = parser.parse_args()

    if args:
        tree_dir = args[0]
    else:
        tree_dir = os.path.join(os.path.dirname(__file__), 'benchtree')
        if not os.path.exists(tree_dir):
            print('Creating tree at {0}: depth={1}, num_dirs={2}, num_files={3}'.format(
                tree_dir, DEPTH, NUM_DIRS, NUM_FILES))
            create_tree(tree_dir)

    if options.scandir == 'generic':
        scandir.scandir = scandir.scandir_generic
    elif options.scandir == 'c':
        if scandir.scandir_c is None:
            print("ERROR: Compiled C version of scandir not found!")
            sys.exit(1)
        scandir.scandir = scandir.scandir_c
    elif options.scandir == 'python':
        if scandir.scandir_python is None:
            print("ERROR: Python version of scandir not found!")
            sys.exit(1)
        scandir.scandir = scandir.scandir_python
    elif options.scandir == 'os':
        if not hasattr(os, 'scandir'):
            print("ERROR: Python 3.5's os.scandir() not found!")
            sys.exit(1)
        scandir.scandir = os.scandir
    elif hasattr(os, 'scandir'):
        scandir.scandir = os.scandir

if args:
        tree_dir = args[0]
    else:
        tree_dir = os.path.join(os.path.dirname(__file__), 'benchtree')
        if not os.path.exists(tree_dir):
            print('Creating tree at {0}: depth={1}, num_dirs={2}, num_files={3}'.format(
                tree_dir, DEPTH, NUM_DIRS, NUM_FILES))
            create_tree(tree_dir)

    if options.scandir == 'generic':
        scandir.scandir = scandir.scandir_generic
    elif options.scandir == 'c':
        if scandir.scandir_c is None:
            print("ERROR: Compiled C version of scandir not found!")
            sys.exit(1)
        scandir.scandir = scandir.scandir_c
    elif options.scandir == 'python':
        if scandir.scandir_python is None:
            print("ERROR: Python version of scandir not found!")
            sys.exit(1)
        scandir.scandir = scandir.scandir_python
    elif options.scandir == 'os':
        if not hasattr(os, 'scandir'):
            print("ERROR: Python 3.5's os.scandir() not found!")
            sys.exit(1)
        scandir.scandir = os.scandir
    elif hasattr(os, 'scandir'):
        scandir.scandir = os.scandir

    if scandir.scandir == getattr(os, 'scandir', None):
        print("Using Python 3.5's builtin os.scandir()")
    elif scandir.scandir == scandir.scandir_c: