def check_password(password, encoded, setter=None, preferred='default'):
    """
    Returns a boolean of whether the raw password matches the three
    part encoded digest.

    If setter is specified, it'll be called when you need to
    regenerate the password.
    """
    if password is None or not is_password_usable(encoded):
        return False

    preferred = get_hasher(preferred)
    hasher = identify_hasher(encoded)

    must_update = hasher.algorithm != preferred.algorithm
    if not must_update:
        must_update = preferred.must_update(encoded)
    is_correct = hasher.verify(password, encoded)
    if setter and is_correct and must_update:
        setter(password)
    return is_correct