Question: I need some help to understand `pushStack`

Here I've made an example where the results using it or not are the same <http://jsfiddle.net/Bz5n9/2/> so I think i really didn't get what is it for.

Thanks!

Answer: 
You're currently adding to the collection, pushing a new collection on the stack that's already the result (you could just return the result of `this.add()`). What this does is instead of pushing `.b` elements on the stack as a new element, it pushes a new set with `.b` elements *and* the `#2` `<li>` you started with.

Instead, you instead should pass the elements directly (no [`.add()`](http://api.jquery.com/add/) call), like this:

```
return this.pushStack(newCollection, "agregate", "");

```

[You can test it out here](http://jsfiddle.net/nick_craver/Bz5n9/3/).
Ben does a good job of explaining it here: 

[http://www.bennadel.com/blog/1739-Using-PushStack-In-jQuery-Plugins-To-Create-
New-Collections.htm](http://www.bennadel.com/blog/1739-Using-PushStack-In-jQuery-Plugins-To-Create-New-Collections.htm)