syntax_data: {"ast_node_type":"variable","tokens":[{"end":52,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let context_mut_ref = Ty::new_task_context(tcx);
context_before: fn transform_async_context<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) -> Ty<'tcx> {