public int getResolution(Choice choice) {
        if (choice.alternatives().size() == 1) return 0;
        if (choice.isEmpty()) throw new IllegalArgumentException("Cannot return a resolution of empty " + choice);
        Integer resolution = choiceResolutions.get(choice);
        if (resolution == null) throw new IllegalArgumentException(this + " has no resolution of " + choice);
        return resolution;
    }
Returns the resolution of a choice.

@return the (0-base) index of the choice made. If the given choice has exactly one alternative,
        0 is always returned (whether or not the choice has been attempted resolved).
@throws IllegalArgumentException if the choice is empty, or if it has multiple alternatives but have not
        been resolved in this
container-search/src/main/java/com/yahoo/search/pagetemplates/engine/Resolution.java