public static TreeSet<IdHistogram> buildVectorIdHistogram(Iterator<FunctionDescription> iter) {
		TreeSet<IdHistogram> table = new TreeSet<IdHistogram>();
		IdHistogram testItem = new IdHistogram();
		while(iter.hasNext()) {
			testItem.id = iter.next().getVectorId();
			if (testItem.id == 0) {
				continue; // Function doesn't have associated vector
			}
			IdHistogram cur = table.floor(testItem);
			if (cur == null || cur.id != testItem.id) {
				cur = new IdHistogram();
				cur.id = testItem.id;
				cur.count = 1;
				table.add(cur);
			}
			else {
				cur.count += 1;
			}
		}
		return table;
	}
@param iter is iterator over functions whose vectors are to be histogrammed
@return the sorted list of pairs (hash,count)
Ghidra/Features/BSim/src/main/java/ghidra/features/bsim/query/client/IdHistogram.java