def sort_colors_descending(g):
    """
    Sort priorities occurring in the game in descending order of priority.
    :param g: a game graph.
    :return: the colors in g sorted in descending order.
    """

    # (player, priority) is a value of the node dictionary. We create a set of the priorities to remove duplicates
    # then we sort it
    return sorted(set(k[1] for k in g.nodes.itervalues()), reverse=True)