syntax_data: {"ast_node_type":"variable","tokens":[{"end":44,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:             let env_ty = tcx.closure_env_ty(
context_before:             let sig = tcx.instantiate_bound_regions_with_erased(args.as_closure().sig());
context_after:                 Ty::new_closure(tcx, def_id, args),