syntax_data: {"ast_node_type":"variable","tokens":[{"end":79,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                     let items = self.collector.tcx.opaque_types_defined_by(id);
context_before:                 if let DefKind::TyAlias = self.collector.tcx.def_kind(id) {
context_after:                     self.collector.opaques.extend(items);