Looking for Antlr grammars

I am trying to learn the tool ANTLR, and I would like to use existing grammar, if available.

I looked in official GitHub Antlr Grammars page and couldnt find a grammar for the NuSMV tool. Is there any other list of grammars that is updated, that can point me to a grammar for NuSMV?

It would be nice to reuse , rather than write the grammar all over again.