hasFilterHandler (hasFilterHandler) {
        if (!arguments.length) {
            return this._hasFilterHandler;
        }
        this._hasFilterHandler = hasFilterHandler;
        return this;
    }
Set or get the has-filter handler. The has-filter handler is a function that checks to see if
the chart's current filters (first argument) include a specific filter (second argument).  Using a custom has-filter handler allows
you to change the way filters are checked for and replaced.
@example
// default has-filter handler
chart.hasFilterHandler(function (filters, filter) {
    if (filter === null || typeof(filter) === 'undefined') {
        return filters.length > 0;
    }
    return filters.some(function (f) {
        return filter <= f && filter >= f;
    });
});

// custom filter handler (no-op)
chart.hasFilterHandler(function(filters, filter) {
    return false;
});
@param {Function} [hasFilterHandler]
@returns {Function|BaseMixin}