syntax_data: {"ast_node_type":"variable","tokens":[{"end":42,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let entry = self.map.get(&input)?;
context_before:     ) -> Option<CacheData<'a, X>> {
context_after:         if let Some(Success { required_depth, ref nested_goals, ref result }) = entry.success