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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def prepare(cls) -> None: """Fill in possibly missing package metadata."""

        if cls.version is None:
            cls.version = find_version(cls.name)
        if cls.long_description is None:
            cls.long_description = cls.parse_readme()
        if cls.packages is None:
            cls.packages = find_packages(cls.root_directory)
        if cls.install_requires is None:
            cls.install_requires = parse_requirements()
        if cls.python_requires is None:
            cls.python_requires = find_required_python_version(cls.classifiers)