Retrieving an array of strings with the golang client

If I want to query for an array of strings using the golang client, I would use this example:

q := `query all($a: string) {
    all(func: eq(name, $a)) {

res, err := txn.QueryWithVars(ctx, q, map[string]string{"$a": "Alice"})
fmt.Printf("%s\n", res.Json)

and it specifies map[string], since we expect an array of strings.

Now, suppose I want to query for an array of structs, where each struct is an array of strings, such as

q := `query all($a: string) {
    all(func: lt(k, $a)) {
  }` ,

for the structure defined by

var decode struct {
		All []struct {
			Uid     string
			l1      string
			l2    string
		        l3    string
		        l4 string


what would be the equivalent argument to QueryWithVars? Would it be map[decode]string{"$a": f})?

It will be same as before, map[string]string.