c3_chart_fn.load = function (args) {
    var $$ = this.internal, config = $$.config;
    // update xs if specified
    if (args.xs) {
        $$.addXs(args.xs);
    }
    // update classes if exists
    if ('classes' in args) {
        Object.keys(args.classes).forEach(function (id) {
            config[__data_classes][id] = args.classes[id];
        });
    }
    // update categories if exists
    if ('categories' in args && $$.isCategorized()) {
        config[__axis_x_categories] = args.categories;
    }
    // use cache if exists
    if ('cacheIds' in args && $$.hasCaches(args.cacheIds)) {
        $$.load($$.getCaches(args.cacheIds), args.done);
        return;
    }
    // unload if needed
    if ('unload' in args) {
        // TODO: do not unload if target will load (included in url/rows/columns)
        $$.unload($$.mapToTargetIds((typeof args.unload === 'boolean' && args.unload) ? null : args.unload), function () {
            $$.loadFromArgs(args);
        });
    } else {
        $$.loadFromArgs(args);
    }
};

c3_chart_fn.unload = function (args) {
    var $$ = this.internal;
    args = args || {};
    $$.unload($$.mapToTargetIds(args.ids), function () {
        $$.redraw({withUpdateOrgXDomain: true, withUpdateXDomain: true, withLegend: true});
        if (args.done) { args.done(); }
    });
};