Update Logger singleton creation, add test and docstring

[kremnik]

What has been done

With this PR, just made a few tweaks to the way we create the singleton instance of the Logger class.

1. The check for the existence of the class instance has been moved from the global dictionary to the Logger's __new__ method.
2. The function get_singletonish_logger() has been replaced with a simple instantiation by calling Logger().
3. A test (in the file test_singleton.py) has been added to verify that the created instances have the same memory address.
4. A brief docstring has been added to the Logger class.
5. .vscode folder has been added to .gitignore.

How to test

make lint && make test

or if you want to test singleton creation only:

python -m pytest tests/test_singleton.py -s --disable-warnings

[serengil]

this should not be added to gitignore because it stores the configuration all developers should follow.

i can update source code from different environments with same auto-linting in that way.

please remove it.

[kremnik]

I understand the importance of consistent configurations across different environments.

But I think keeping the .vscode folder in the repository can lead to 2 potential issues:

1. The .vscode folder often contains individual developer settings, which might conflict with personal preferences or setups.
2. Sometimes, .vscode/* files may include sensitive information specific to a developer's local environment.

To achieve consistency, it is possible to save essential settings in .vscode/settings.json while ignoring other files from this folder.

Let me know your thoughts!

[serengil]

current .vscode in the source code does not have any sensitive information. still thinking it is important to have it.

[serengil]

In previous design, we can either create a singleton logger and standalone logger. in case of creating standalone one, module is being set and this can be printed in the log messages. With this design, logger must be singleton. How can be highlighted the triggered module?

ps: not a negative comment, just to discuss

[kremnik]

I haven't seen the Logger being used as a non-singleton in the current design, but it's possible I may have missed it. If having a standalone Logger with module-specific messages is needed, I can add argument checking when the Logger is instantiated using __new__ method. If it includes a "module" parameter, it creates a new standalone Logger instead of a singleton.
Let me know if this approach works for you!

[serengil]

@kremnik never mind the stand alone thing. That feature is available but not being used at all.

It is good to go if you restore vscode folder.

[serengil]

Thank you for your contribution