gistfile1.txt

(function (doc) {
    return doc.type === 'user_notification' && !doc.read && doc.ping_timestamp != null ? emit(doc.ping_timestamp, [doc.user]) : null;
});

(function (key, values, rereduce) {
    var result = {  };
    for (var value = null, _js_idx1 = 0; _js_idx1 < values.length; _js_idx1 += 1) {
        value = values[_js_idx1];
        for (var uid = null, _js_idx2 = 0; _js_idx2 < value.length; _js_idx2 += 1) {
            uid = value[_js_idx2];
            result[uid] = null;
        };
    };
    return Object.keys(result);
});