def _build_package_finder(
        self,
        options,               # type: Values
        session,               # type: PipSession
        target_python=None,    # type: Optional[TargetPython]
        ignore_requires_python=None,  # type: Optional[bool]
    ):
        # type: (...) -> PackageFinder
        """
        Create a package finder appropriate to this requirement command.

        :param ignore_requires_python: Whether to ignore incompatible
            "Requires-Python" values in links. Defaults to False.
        """
        link_collector = make_link_collector(session, options=options)
        selection_prefs = SelectionPreferences(
            allow_yanked=True,
            format_control=options.format_control,
            allow_all_prereleases=options.pre,
            prefer_binary=options.prefer_binary,
            ignore_requires_python=ignore_requires_python,
        )

        return PackageFinder.create(
            link_collector=link_collector,
            selection_prefs=selection_prefs,
            target_python=target_python,
        )

        Create a package finder appropriate to this requirement command.

        :param ignore_requires_python: Whether to ignore incompatible
            "Requires-Python" values in links. Defaults to False.
        
product/gradle-plugin/src/main/python/pip/_internal/cli/req_command.py