from collections.abc import Iterator
#编写一个迭代器,通过循环语句,实现对某个正整数的依次递减1,直到0.
class Descend(Iterator):
 def __init__(self,N):
 self.N=N
 self.a=0
 def __next__(self):
 while self.a<self.N:
 self.N-=1
 return self.N
 raise StopIteration
 
descend_iter=Descend(10)

try:
 for i in descend_iter:
 print(i)
except StopIteration as e:
 print('迭代结束')