From what I understand, collections in USD can specify membership in either relationship-mode or expression-mode. I have a case that might benefit from using expression-mode, but I wonder how to access that in Solaris?

I can set the required collection:membershipExpressionwith a Python LOP, but I feel I might be missing something obvious (an option on the Collection LOP?)

This is how I'm doing it now. Just wondering if it's the best/only way?