app.get('/', function(req, res) {
    //res.write(json); is good but we need to call res.end() to end the response
    //what i really should have done is this:
    res.writeHead(200, {"Content-Type": "application/json"}); // not sure if this line is needed!
    res.end(json);


    // res.end(json); is equal to: res.write(json); res.end();
});