Python error runtimeerror:dictionary changed size during iteration

Pythonn error message:

C:\Users\Administrator\AppData\Local\Programs\Python\Python36-32\python.exe c:/users/administrator/ pycharmprojects/pythondemo/maptest.py
Traceback (most recent):
  File "c:/users/administrator/pycharmprojects/pythondemo/maptest.py", line 5, <module>
    For line in Maps.keys ():
Runtimeerror:dictionary changed size during iteration

# Python2 The elements in the dictionary while the traversal is implemented, and the error message is run in Python3:
"""
C:\Users\Administrator\AppData\Local\Programs\Python\Python36-32\python.exe c:/users/administrator/ pycharmprojects/pythondemo/maptest.py
Traceback (most recent):
  File "c:/users/administrator/pycharmprojects/pythondemo/maptest.py", line 5, <module>
    For line in Maps.keys ():
Runtimeerror:dictionary changed size during iteration
"""
# maps = {1: "Li Ming", 2: "Danny"}
# for line in Maps.keys ():
#     if (line = = 2):
#         Maps.pop (line)
# Print (MAPS)



# Python3 to delete elements in a dictionary while implementing traversal
Maps = {1: "Li Ming", 2: "Danny"}
For line in list (Maps.keys ()):
    if (line = = 2):
        Maps.pop (line)
Print (MAPS)

Python error runtimeerror:dictionary changed size during iteration