const promisify = require('promisify-func');

const p = (url) => url;

promisify(p)(url).then(res => {
    //res == url
})

const t = () => {throw new Error()};

promisify(t)().catch(err => {
    //err == new Error()
})

//will do nothing for Promises
promisify(Promise.resolve("abc")).then(res => {
    //res == abc
})