public void reset() {
        if (flattenedItems != null)
            previousQuerySize = flattenedItems.size();
        currentIndex = 0;
        traceIndentation = "";
        flattenedItems = new java.util.ArrayList<>();
        flatten(query.getModel().getQueryTree().getRoot(), 0, flattenedItems);
    }
Resets the item iterator to point to the first item
container-search/src/main/java/com/yahoo/prelude/semantics/engine/Evaluation.java