unbounded variable

[deanhystad]

I am unfamiliar with dis module.so I did not understand the blue sections of your reply.

You can read all about the python disassembler here:
https://docs.python.org/3/library/dis.html

why the error is not created in main1 function

There are no assignments in main1, so main1 doesn't make a local variable. This would generate an error

def main1():
    print(take_sum) 

If you didn't have a function named "take_sum" in the global namespace. When accessing variables python first looks local, then enclosed, global and finally built-in.