Where the third argument to setTimeout?

In the textbook on learn.javascript.ru read the Chapter on generators.
There is an example of the library use "co".
co(function*() {
 let res = yield new Promise(resolve => {
 setTimeout(resolve, 1000, 1);

 return res;

And that is something I can not catch up with where the third argument (1) timer?
July 4th 19 at 23:30
1 answer
July 4th 19 at 23:32
Need somewhere to watch about it
Apparently, just a set of parameters for the called function. And, parameters can be more
Here is an example

What is the function of resolve? Tried to write not 1, but 2, 3, 4 - the result changes?
Thanks, already figured out.
In promis is passed to the console.log in place resolve. - Howell commented on July 4th 19 at 23:35

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