Promise-CB

Promise-callback helper functions.

fromCallback

Creates a Promise from a callback-style function.

Example:
``js
fromCallback(cb => fs.readFile(file, cb));
`




toCallback

Calls a callback function with the result of a promise once it settles.

Example:
`js
toCallback(promise, (err, result) => {
if (err) console.error(err.stack);
else doSomething(result);
});
``