{"ast_node_type":"other","tokens":[{"end":56,"kind":"keyword","start":0,"text":"ty::BoundRegionKind::ClosureEnv"}]}
            ty::BoundRegionKind::ClosureEnv => sym::env,
            ty::BoundRegionKind::Named(def_id) => self.type_checker.tcx().item_name(def_id),
            ty::BoundRegionKind::NamedAnon(_) => bug!("only used for pretty printing"),