CHLCC AFS Unpack

import struct
from itertools import zip_longest
from functools import partial

def grouper(iterable, n, fillvalue=None):
    args = [iter(iterable)] * n
    return zip_longest(*args, fillvalue=fillvalue)

with open('SCENE00.AFS', 'rb') as f:
    f.seek(4)
    num_of_files = struct.unpack('<I', f.read(4))[0]
    TOC = (struct.unpack('<' + 'I' * 2 * num_of_files,
                         f.read(8 * num_of_files)))
    TOC_pos, TOC_size = struct.unpack('<II', f.read(8))
    filenames = []
    f.seek(TOC_pos)
    for x in range(num_of_files):
        s = b''
        pos = f.tell()
        for byte in iter(partial(f.read, 1), b'\x00'):
            s += byte
        filenames.append(s)
        f.seek(pos + 0x30)
    for filename, (fileoffset, filesize) in zip(filenames, grouper(TOC, 2)):
        f.seek(fileoffset)
        with open(filename, 'wb') as g:
            g.write(f.read(filesize))