function sortedGroupBy(list, groupByIter, sortByIter) {
    if (_.isArray(groupByIter)) {
        function groupBy(obj) {
            return _.map(groupByIter, function(key, value) {
                return obj[key];
            });
        }
    } else {
        var groupBy = groupByIter;
    }
    if (_.isArray(sortByIter)) {
        function sortBy(obj) {
            return _.map(sortByIter, function(key, value) {
                return obj[key];
            });
        }
    } else {
        var sortBy = sortByIter;
    }
    var groups = _.groupBy(list, groupBy);
    _.each(groups, function(value, key, list) {
        list[key] = _.sortBy(value, sortBy);
    });
    return groups;
}