Update onNext function in Observer
const Rx = require('rx');
const hound = require('hound');
const jp = require('jupyter-paths');

const watcher = hound.watch(jp.paths.runtime[0]);

function isKernelJSON(filepath) {
    var name = path.basename(filepath);
    return name.startsWith('kernel') && name.endsWith('.json');
}

const source = Rx.Observable.fromEvent(watcher, 'create')
                .filter(function(value, index, observable) {
                    return isKernelJSON(value);
                });

const observer = Rx.Observer.create(
    function (value) {
        return value;
    },
    function (error) {
        console.log(error);
    }
);

module.exports = Rx.Subject.create(observer, source);

const Rx = require('rx');
const hound = require('hound');
const jp = require('jupyter-paths');

const watcher = hound.watch(jp.paths.runtime[0]);

function isKernelJSON(filepath) {
    var name = path.basename(filepath);
    return name.startsWith('kernel') && name.endsWith('.json');
}

const source = Rx.Observable.fromEvent(watcher, 'create')
                .filter(function(value, index, observable) {
                    return isKernelJSON(value);
                });

const observer = Rx.Observer.create(
    function (value) {
        callback(value);
    },
    function (error) {
        console.log(error);
    }
);

module.exports = Rx.Subject.create(observer, source);
