def overall_jaccard_index_calc(jaccard_list):
    """
    Calculate overall jaccard index.

    :param jaccard_list : list of jaccard index for each class
    :type jaccard_list : list
    :return: (jaccard_sum , jaccard_mean) as tuple
    """
    try:
        jaccard_sum = sum(jaccard_list)
        jaccard_mean = jaccard_sum / len(jaccard_list)
        return jaccard_sum, jaccard_mean
    except Exception:
        return 'None'
