syntax_data: {"ast_node_type":"function","tokens":[{"end":83,"kind":"keyword","start":0,"text":"fn"}]}
source_snippet:     fn try_fold_region(&mut self, r: I::Region) -> Result<I::Region, Self::Error> {
context_before:     // and has no `super_fold_with` method to call.
context_after:         Ok(r)