{"ast_node_type":"other","tokens":[{"end":92,"kind":"keyword","start":0,"text":"(idx.to_index()"}]}
        (idx.to_index() < self.num_variants()).then_some(VariantDef { idx, adt_def: *self })
    pub fn variant(&self, idx: VariantIdx) -> Option<VariantDef> {
    }