Function headless_lms_models::user_exercise_states::get_user_exercise_state_if_exists

pub async fn get_user_exercise_state_if_exists(
    conn: &mut PgConnection,
    user_id: Uuid,
    exercise_id: Uuid,
    course_instance_or_exam_id: CourseInstanceOrExamId
) -> ModelResult<Option<UserExerciseState>>