def product(xs, empty=1):
    """Computes the product along the elements in an iterable.

    Args:
        xs: Iterable containing numbers.
        empty: ??

    Returns: Product along iterable.

    """
    result = None
    for x in xs:
        if result is None:
            result = x
        else:
            result *= x
    if result is None:
        result = empty
    return result
