Hi, I've tried to perform a query which returns localized fields. I would like to pass the localization as variables such as: ```Go var variables = map[string]string{ "$local":"en:fr:.", } const q = ` { items(func: has(item)){ id: uid short_description: title@$local. long_description: description@$local. } } ` response, err := txn.QueryWithVars(ctx, q,variables) ``` I'm getting a lexical error when I try this. It would make sense to be able to query with a local as variable