syntax_data: {"ast_node_type":"variable","tokens":[{"end":50,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let adt_def = tcx.adt_def(wrapper_def_id);
context_before:     fn new_generic_adt(tcx: TyCtxt<'tcx>, wrapper_def_id: DefId, ty_param: Ty<'tcx>) -> Ty<'tcx> {
context_after:         let args = GenericArgs::for_item(tcx, wrapper_def_id, |param, args| match param.kind {