python encrypt large file with md5

md5_for_large_file.py

def md5_for_file(path):
    path = path.encode('utf-8')
    md = hashlib.md5()
    block_size = 128 * md.block_size
    with open(path, 'rb') as f:
        for chunk in iter(lambda: f.read(block_size), b''):
            md.update(chunk)
    return md.hexdigest()