def METHOD_NAME(self, username, course_id):
    """
    Get the anonymous user id for a user.
    Args:
        username(str): username of a user.
        course_id(str): course id of particular course.
    Returns:
        A unique anonymous_user_id for (user, course) pair.
        None for Non-staff users.
    """
    if not self.get_current_user().opt_attrs.get(ATTR_KEY_USER_IS_STAFF):
        return None
    try:
        user = get_user_by_username_or_email(username_or_email=username)
    except User.DoesNotExist:
        return None
    course_id = CourseKey.from_string(course_id)
    return anonymous_id_for_user(user=user, course_id=course_id)