syntax_data: {"ast_node_type":"other","tokens":[{"end":50,"kind":"keyword","start":0,"text":"self.map.borrow_mut().retain(|key,"}]}
source_snippet:         self.map.borrow_mut().retain(|key, eval| {
context_before:         debug!(?dfn, "on_failure");
context_after:             if !eval.from_dfn >= dfn {