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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 get_theme_dir():
 """ Returns path to directory containing this package's theme. This is designed to be used when setting the ``html_theme_path`` option within Sphinx's ``conf.py`` file. """

    return os.path.abspath(os.path.join(os.path.dirname(__file__), "theme"))