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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 setup(app):
 """ This isn't used in Production, but allows this module to be used as a standalone extension. """


    app.add_directive('readthedocs-embed', EmbedDirective)
    app.add_config_value('readthedocs_embed_project', '', 'html')
    app.add_config_value('readthedocs_embed_version', '', 'html')
    app.add_config_value('readthedocs_embed_doc', '', 'html')

    return app