I am getting a NameError that is not defined and not sure why it happen

[rick0922]

1st you should avid using exec
It does work:

>>> def test():
...     exec("a=100")
...     print(a)
... 
>>> test()
100
>>>

The proper way:

>>> def test():
...     a = 100
...     print(a)
... 
>>> test()
100
print(a)

>>> def test():
...     exec("a=100")
...     print(a)
...
>>> test()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 3, in test
NameError: name 'a' is not defined

Which version are you using? I am using 3.9.5 and it does not work.