Advance Formula If-Then-Else and Contains

I'm trying to write the expression below, where if PO_ItemCategory contains '131' string, the destination DE will say either Yes or No.

(condition contains(PO_ItemCategory,'131')? 'Yes' : No') 

But I am getting this error:

@1:12 parsing error in 'contains'

I'm not familiar with this programming language yet but what language is it using so I can check for references?

Thanks'!

Marvin