Stata 18 introduced an auto-backup feature which creates a temporary file while a code file is open it its IDE.
These auto-backup files are analogous to the [Microsoft Office backup files that are gitignored](https://github.com/github/gitignore/blob/main/Global/MicrosoftOffice.gitignore).
[Ref](https://www.stata.com/manuals/gsm13.pdf):
> The Do-file Editor now creates a backup file whenever it opens a document or creates a new one.
> When an existing document is opened, Stata creates a backup file of a document that is saved to disk
> in the same directory using the existing document’s filename prefixed with ~ and with the extension
> .stswp. When you edit a new and unsaved document, it saves the backup file to the temp directory.
> When a document is closed, the backup file is deleted. However, if Stata does not exit cleanly because
> of a power outage or a computer crash, the backup file is left behind.
Add ruff cache.
ruff tool: https://github.com/charliermarsh/ruff
ruff is becoming a very popular tool often run in pre-commit and aim to replace Flake8 (plus dozens of plugins), isort, pydocstyle, yesqa, eradicate, pyupgrade, and autoflake, all while executing tens or hundreds of times faster than any individual tool.
Added undo-tree, which is a popular package for undoing changes made to a file. It leaves hidden files everywhere, and can litter up a repository if not ignored.
I have to add `*.~undo-tree~` to every `.gitignore` file in every repository I am working in. As you can guess, this gets very tedious.
Unity packages were already ignored, but it seems in recent versions of Unity these also generate meta files for these. If the meta file isn't also ignored, the person who imports an asset containing a .unitypackage file could accidentally commit the meta files. For another who downloads those meta files, Unity would automatically delete them since they don't have the .unitypackage. The the importer commits them again and the cycle goes on and on until someone like me gets fed up.
This fixes that inconsistency by adding the *.unitypackage.meta to the ignore list.
Shane Reetz