159. implement promisify()

Let's take a look at following error-first callback.

const callback = (error, data) => {  if (error) {    // handle the error  } else {    // handle the data  }}

Now think about async functions that takes above error-first callback as last argument.

const func = (arg1, arg2, callback) => {  // some async logic  if (hasError) {    callback(someError)  } else {    callback(null, someData)  }}

You see what needs to be done now. Please implement promisify() to make the code better.

const promisedFunc = promisify(func)promisedFunc().then((data) => {  // handles data}).catch((error) => {  // handles error})