You're looking at StableBuild's Deleted PyPI mirror - where we index all deleted packages from the Python package registry.
filesystem-python was reported malicious
OSV:MAL-2025-6506 - Malicious code in filesystem-python (PyPI)

filesystem-python
0.1.2

This version was deleted from PyPI around 2025-06-20. Installing fails with:
$ pip3 install filesystem-python==0.1.2 ERROR: Could not find a version that satisfies the requirement filesystem-python==0.1.2

Install through StableBuild

You can install this package from StableBuild's PyPI snapshots from before the version was deleted:
pip3 install \ -i https://YOUR_API_KEY.pypimirror.stablebuild.com/2025-06-19/ \ filesystem-python==0.1.2
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Or, download files manually

And install manually via pip: