syntax_data: {"ast_node_type":"variable","tokens":[{"end":46,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let node = tcx.hir_node_by_def_id(def_id);
context_before: fn fn_sig_spans(tcx: TyCtxt<'_>, def_id: LocalDefId) -> impl Iterator<Item = Span> {
context_after:     if let Some(decl) = node.fn_decl() {