{"ast_node_type":"other","tokens":[{"end":81,"kind":"keyword","start":0,"text":"expr.for_each_metavar(LockstepIterSize::Unconstrained,"}]}
            expr.for_each_metavar(LockstepIterSize::Unconstrained, |lis, ident| {
        TokenTree::MetaVarExpr(_, expr) => {
                lis.with(lockstep_iter_size(