{"ast_node_type":"other","tokens":[{"end":99,"kind":"keyword","start":0,"text":"TyKind::RigidTy(RigidTy::Closure(_def,"}]}
            TyKind::RigidTy(RigidTy::Closure(_def, args)) => Some(with(|cx| cx.closure_sig(args))),
            TyKind::RigidTy(RigidTy::FnPtr(sig)) => Some(sig.clone()),
            _ => None,