/**
 * The ColorKey is both the key and the value in our enhanced
 * binary tree.
 */
class ColorKey implements SearchKey {
    String key;
    String colorValue;

    public ColorKey(String k, String v) {
        key = k;
        colorValue = v;
    }

    private void verifyType(SearchKey k) {
        if (! (k instanceof ColorKey))
            throw new RuntimeException("You cannot mix keys here.");
    }

    public int compareKey(SearchKey b) {
        verifyType(b);
        return key.compareTo(((ColorKey) b).key);
    }

    public boolean equalKey(SearchKey o) {
        return (compareKey(o) == 0);
    }

    public String toString() {
        return "ColorKey:: '"+key+"' ==> '"+colorValue+"'";
    }
}