At what point or location does the -L option get configured by setuptools.Extension?

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The -L option is used to specify additional library search directories during the linking phase of building a C/C++ extension module. This option can be configured in the library_dirs parameter of setuptools.Extension. The library_dirs parameter is a list of directories to search for libraries when linking the extension module. The option is configured at the point where the Extension object is created in the setup.py file, which is used by setuptools to build and distribute Python packages.