I'm incorporating this library into a project where I want to let users create formulas that check against certain fields. This is mostly working, but I've hit a small roadblock when trying to create a x exists suffix operator that basically checks x != nil. This generally works, but fails in certain nesting conditions.

It might have to do something with operator precedence, as changing the order fixes one case but then causes another test case to fail. I'd appreciate some feedback on how to fix this or how to debug this.

The strange thing is that it works fine perfectly if it's a prefix operator (didset X in my example), though I'd prefer the suffix variant.

The full code sample is here, which is a minor modification of the code from the template example in this repo: https://gist.github.com/nighthawk/060475d0ded20788e9269054e152d76d

Any help would be much appreciated!