function isSet(x) {
    if (!setSize || !x || typeof x !== 'object') {
        return false;
    }
    try {
        setSize.call(x);
        try {
            mapSize.call(x);
        } catch (m) {
            return true;
        }
        return x instanceof Set; // core-js workaround, pre-v2.5.0
    } catch (e) {}
    return false;
}
Invoke callback when the response has finished, useful for
cleaning up resources afterwards.

@param {object} msg
@param {function} listener
@return {object}
@public