public String toString() {
    	if(ranges.size() == 0) {
    		return "{[]}";
    	}

   		sortRanges();
    	StringBuilder stringBuilder = new StringBuilder();
    	stringBuilder.append("{");
    	int index = -1;
    	int last = ranges.size() - 1;
    	
    	for(PERange range : ranges) {
    		index++;
    		stringBuilder.append(range);
    		if(index < last) {
    			stringBuilder.append(",");
    		}
    	}
    	
    	stringBuilder.append("}");
    	return stringBuilder.toString();
    }