public static Key[] getUniqueKeys(IndexMatch[] matches) {
SortedSet set = new TreeSet();
for (int i = 0; i < matches.length; i++) {
set.add(matches[i].getKey());
}
return (Key[]) set.toArray(EmptyKeys);
}
/**
* andKeySets takes several sets of unique Keys and returns the
* ANDed set (elements that exist in all sets). The first dimension