def pbkdf2_bin(data, salt, iterations=DEFAULT_PBKDF2_ITERATIONS,
               keylen=None, hashfunc=None):
    """Returns a binary digest for the PBKDF2 hash algorithm of `data`
    with the given `salt`. It iterates `iterations` time and produces a
    key of `keylen` bytes. By default SHA-1 is used as hash function,
    a different hashlib `hashfunc` can be provided.

    .. versionadded:: 0.9

    :param data: the data to derive.
    :param salt: the salt for the derivation.
    :param iterations: the number of iterations.
    :param keylen: the length of the resulting key.  If not provided
                   the digest size will be used.
    :param hashfunc: the hash function to use.  This can either be the
                     string name of a known hash function or a function
                     from the hashlib module.  Defaults to sha1.
    """
    if isinstance(hashfunc, string_types):
        hashfunc = _hash_funcs[hashfunc]
    elif not hashfunc:
        hashfunc = hashlib.sha1
    salt = to_bytes(salt)
    mac = hmac.HMAC(to_bytes(data), None, hashfunc)
    if not keylen:
        keylen = mac.digest_size
    def _pseudorandom(x, mac=mac):
        h = mac.copy()
        h.update(x)
        return bytearray(h.digest())
    buf = bytearray()
    for block in range_type(1, -(-keylen // mac.digest_size) + 1):
        rv = u = _pseudorandom(salt + _pack_int(block))
        for i in range_type(1 - iterations):
            u = _pseudorandom(bytes(u))
            rv = bytearray(starmap(xor, izip(rv, u)))
        buf.extend(rv)
    return bytes(buf[:keylen])
dataset/ETHPy150Open GeekTrainer/Flask/Work/Trivia - Module 5/env/Lib/site-packages/werkzeug/security.py/pbkdf2_bin/swapped operands of `-`