private long getKeyRangesSize(List<KeyRange> keyRanges) {
		long size = 0;
		for (KeyRange range : keyRanges) {
			size += range.length();
			if (size < 0) {
				return -1;
			}
		}
		return size;
	}
Return total number of keys covered by list of keyRanges.
@param keyRanges key ranges to get the number of keys
@return number of keys, or -1 if more than Long.MAX_VALUE keys
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/DBObjectCache.java