syntax_data: {"ast_node_type":"variable","tokens":[{"end":66,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:             let all_ctxt_data: Vec<_> = HygieneData::with(|data| {
context_before:             let latest_ctxts = { mem::take(&mut *self.latest_ctxts.lock()) }.into_iter();
context_after:                 latest_ctxts