def METHOD_NAME(user_id, course_key, usage_key):
    """
    Given a user_id, course_key, and subsection usage_key,
    creates a new ``PersistentSubsectionGrade``.
    """
    from lms.djangoapps.courseware.courses import get_course
    from django.contrib.auth import get_user_model
    course = get_course(course_key, depth=None)
    subsection = course.get_child(usage_key)
    if not subsection:
        raise Exception('Subsection with given usage_key does not exist.')
    user = get_user_model().objects.get(id=user_id)
    subsection_grade = CreateSubsectionGrade(subsection, course_data.CourseData(user, course=course).structure, {}, {})
    return subsection_grade.update_or_create_model(user, force_update_subsections=True)