Find out if a block is a part of a double chest?

I was wondering if there was any way to find out if a chest block is a part of a double chest and, if so, there was a way to get the other chest block. This is for my Cabinet plugin to make things easier for me, and to make it easier to implement a new feature for it.

 

You could always iterate through the x-axis and z-axis on each side of the block until you find another chest, or if there isn't one then it's a single chest. That's how I'd do it.

 

That's what I'm doing now, but it seems like there may be a better way. I can't explain it very well, but it sort of makes sense in my head.

 

its at most, 4 calls, that is far from bad.

 

What they're describing is exactly how it's done in the minecraft source.