public long decrement(T key, long count) {
ensureKey(key);
count = map.get(key) - count;
map.put(key, count);
total -= count;
return count;
}
public long increment(T key, long count) {
ensureKey(key);
count = map.get(key) + count;
map.put(key, count);
total += count;
return count;
}
