private String concatenate(List<Token> tokens) {
        StringBuilder s = new StringBuilder();
        for (Token t : tokens) {
            s.append(t.toString());
        }
        return s.toString();
    }
Returns an item and whether it had an explicit index ('indexname:' prefix).

@param indexPath the index name prefix this is in the context of, only non-empty if this is
                 inside a sameElement. The path includes the index name and the trailing dot.
@return an item and whether it has an explicit index, or a Pair with the first element null if none
container-search/src/main/java/com/yahoo/prelude/query/parser/StructuredParser.java