How do you adjust the histogram levels in Photos (NOT the RGB)

[Haswell]

I've been working with the somewhat new Photos app and I don't like it compared to iPhoto. My biggest issue is that there's no way to adjust the histogram levels like you can do in iPhoto.

I am missing something or is there a third party plugin I can add to get this feature back?

 

[Alexander B.]

Click edit, then click "Add" in the top right corner next to "ADJUSTMENTS" and select "Levels". That's it