syntax_data: {"ast_node_type":"variable","tokens":[{"end":14,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let ctxt =
context_before:     let (parent, expn_id, transparency) = decode_data(d, raw_id);
context_after:         HygieneData::with(|hygiene_data| hygiene_data.alloc_ctxt(parent, expn_id, transparency));