const app = require("express")();
const uu = require("uuport");

uu().then(port => {
    app.listen(port, () => {
        console.log("listening on port " + port); 
    });
});

const app = require("express")();
const uu = require("uuport");

(async () => {
    app.listen(await uu());
})();

const app = require("express")();
const uu = require("uuport");

(async () => {
    app.listen(await uu(3000, 5000)); //await uu(min=3000, max=5000);
})();