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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 base_app(import_name, instance_path=None, static_folder=None, static_url_path='/static', template_folder='templates', instance_relative_config=True, app_class=Flask):
 """Invenio base application factory. If the instance folder does not exists, it will be created. :param import_name: The name of the application package. :param env_prefix: Environment variable prefix. :param instance_path: Instance path for Flask application. :param static_folder: Static folder path. :param app_class: Flask application class. :returns: Flask application instance. .. versionadded: 1.0.0 """

    configure_warnings()

    # Create the Flask application instance
    app = app_class(
        import_name,
        instance_path=instance_path,
        instance_relative_config=instance_relative_config,
        static_folder=static_folder,
        static_url_path=static_url_path,
        template_folder=template_folder,
    )

    # Create instance path if it doesn't exists
    try:
        if instance_path and not os.path.exists(instance_path):
            os.makedirs(instance_path)
    except Exception:  # pragma: no cover
        app.logger.exception(
            'Failed to create instance folder: "{0}"'.format(instance_path)
        )

    return app