public String toString(){
			StringBuilder result = new StringBuilder("{");
			for(Map.Entry<Class<? extends Pet>, Integer> pair:entrySet()){
				result.append(pair.getKey().getSimpleName());
				result.append("=");
				result.append(pair.getValue());
				result.append(", ");
			}
			result.delete(result.length()-2, result.length());
			result.append("}");
			return result.toString();
		}