For a time input on a form, how do I match the "latest" field in the condition element?

I have a form with this input:Time Range-60d@d@d@d What I want to do is that, whenever someone picks a time range where `time_tok.latest` is "now", I will force it back to **@d** (because our index won't contain today data). However, for time input, I don't know how to compare the `latest` part of the `value`. The above code doesn't work. Does anyone know the right way? - Patrick