python错误之RuntimeError: dictionary changed size during iteration

pythonn报错信息：

C:\Users\Administrator\AppData\Local\Programs\Python\Python36-32\python.exe C:/Users/Administrator/PycharmProjects/pythondemo/maptest.py
Traceback (most recent call last):
  File "C:/Users/Administrator/PycharmProjects/pythondemo/maptest.py", line 5, in <module>
    for line in maps.keys():
RuntimeError: dictionary changed size during iteration

python2中实现遍历的同时删除字典中的元素；python3中运行报错信息：

C:\Users\Administrator\AppData\Local\Programs\Python\Python36-32\python.exe C:/Users/Administrator/PycharmProjects/pythondemo/maptest.py

Traceback (most recent call last):

  File "C:/Users/Administrator/PycharmProjects/pythondemo/maptest.py", line 5, in <module>

    for line in maps.keys():

RuntimeError: dictionary changed size during iteration

# maps = {1:"李明",2:"丹尼"}

# for line in maps.keys():

#     if(line == 2):

#         maps.pop(line)

# print(maps)

　　

python3中实现遍历的同时删除字典中的元素

maps = {1:"李明",2:"丹尼"}

for line in list(maps.keys()):

    if(line == 2):

        maps.pop(line)

print(maps)