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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 course_menu(course, template_helper):
 """ Displays the link to the scoreboards on the course page, if the plugin is activated for this course """

    scoreboards = course.get_descriptor().get('scoreboard', [])

    if scoreboards != []:
        return str(template_helper.get_custom_renderer('frontend/plugins/scoreboard', layout=False).course_menu(course))
    else:
        return None