othersGrouper (grouperFunction) {
        if (!arguments.length) {
            return this._othersGrouper;
        }
        this._othersGrouper = grouperFunction;
        return this;
    }
Get or set the grouper function that will perform the insertion of data for the *Others* slice
if the slices cap is specified. If set to a falsy value, no others will be added.

The grouper function takes an array of included ("top") items, and an array of the rest of
the items. By default the grouper function computes the sum of the rest.
@memberof CapMixin
@instance
@example
// Do not show others
chart.othersGrouper(null);
// Default others grouper
chart.othersGrouper(function (topItems, restItems) {
    var restItemsSum = d3.sum(restItems, _chart.valueAccessor()),
        restKeys = restItems.map(_chart.keyAccessor());
    if (restItemsSum > 0) {
        return topItems.concat([{
            others: restKeys,
            key: _chart.othersLabel(),
            value: restItemsSum
        }]);
    }
    return topItems;
});
@param {Function} [grouperFunction]
@returns {Function|CapMixin}