Avoid relative imports in Python scripts

[Kai Aoki]

Many places in the current codebase have relative imports to common utility modules.

# import original modules
sys.path.append('../../util')

It is best to avoid this, as the results will depend on the directory at run time.

https://chat.openai.com/share/6e8b7c33-f160-40ef-8446-b9ef2de82c8d

[Kai Aoki]

MEMO:

It seems that arg_util is also assumed to be executed in the script directory, so
os.chdir(str(Path(__file__).resolve().parents[0]))
It might be easier to do so.