syntax_data: {"ast_node_type":"other","tokens":[{"end":49,"kind":"keyword","start":0,"text":"(def_id,"}]}
source_snippet:     (def_id, sizedness): (DefId, SizedTraitKind),
context_before:     tcx: TyCtxt<'tcx>,
context_after: ) -> Option<ty::EarlyBinder<'tcx, Ty<'tcx>>> {