写一段时间的验证循环，确保thatt=的用户类型中的小数量之间

蟒蛇检查，如果输入()给出了错误

try:
    # Note: Python 2.x users should use raw_input, the equivalent of 3.x's input
    age = int(input("Please enter your age: "))
except ValueError:
    print("Sorry, I didn't understand that.")
else:
	if age >= 18: 
    	print("You are able to vote in the United States!")
	else:
    	print("You are not able to vote in the United States.")