Need Examples of "Get Height of Event/Target Entity"

I literally just need examples of correct/working procedures using the Get Height of Entity block. I can't seem to get it to work correctly/I don't know how to make it fit properly in a procedure/I can't find any examples of it being used anywhere on the internet.

For reference, I'm trying to use it for a quicksand damage procedure, where the entity won't start taking damage until its head/upper region is within a quicksand block. I have a rough method I currently use from a tutorial some time back, but I don't like it, it's messy, and it interacts weirdly with any entity that isn't exactly 2 blocks tall. 

So literally ANY examples of that procedure block correctly in use would be wonderful. Screenshots preferred, I'm a visual learner.