syntax_data: {"ast_node_type":"variable","tokens":[{"end":43,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let item = tcx.hir_expect_item(def_id);
context_before: fn impl_spans(tcx: TyCtxt<'_>, def_id: LocalDefId) -> impl Iterator<Item = Span> {
context_after:     if let hir::ItemKind::Impl(impl_) = item.kind {