# Python {#setup-hook-python}
Adds the `python.sitePackages` subdirectory (i.e. `lib/pythonX.Y/site-packages`) of each build input to the `PYTHONPATH` environment variable.
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Title: Python Setup Hook
Summary
This section describes the Python setup hook for Nix. It automatically adds the `site-packages` subdirectory of each build input to the `PYTHONPATH` environment variable, making Python packages available during the build process.