def split_url(url):
    """
    Split the given URL ``base#anchor`` into ``(base, anchor)``,
    or ``(base, None)`` if no anchor is present.

    In case there are two or more ``#`` characters,
    return only the first two tokens: ``a#b#c => (a, b)``.

    :param string url: the url
    :rtype: list of str
    """
    if url is None:
        return (None, None)
    array = url.split("#")
    if len(array) == 1:
        array.append(None)
    return tuple(array[0:2])