python 标志 python设置标志位

a=['a',1,2,3,4]
b=['b',1,2,3,4]
c=['c',1,2,3,4]
d=['d',1,2,3,4]
break_flag=0
while break_flag==0:
y_n=input('a,yes or no:')
if y_n == 'no':
break
elif y_n == 'yes':
for i in a:
print(i)
while break_flag ==0:
y_n_2=input('b,yes or no:')
if y_n_2=='no':
print('退出')
break_flag=1
elif y_n_2=='yes':
for j in b:
print(j)
while break_flag==0:
y_n_3=input('c,yes or no:')
if y_n_3 == 'no':
print('退出。。。')
break_flag=1
elif y_n_3 == 'yes':
for k in c:
print(k)
while break_flag == 0:
y_n_4 = input('d,yes or no:')
if y_n_4=='no':
print('退出')
break_flag =1
elif y_n_4 =='yes':
for n in d:
print(n)
if break_flag==1:
break