def countZipFileChunks(filename, chunksize):
    """
    Predict the number of chunks that will be extracted from the entire
    zipfile, given chunksize blocks.
    """
    totalchunks = 0
    zf = ChunkingZipFile(filename)
    for info in zf.infolist():
        totalchunks += countFileChunks(info, chunksize)
    return totalchunks

    Predict the number of chunks that will be extracted from the entire
    zipfile, given chunksize blocks.
    
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/zipstream.py