pub async fn insert_exercise_slide_submission(
    conn: &mut PgConnection,
    exercise_slide_submission: NewExerciseSlideSubmission,
) -> ModelResult<ExerciseSlideSubmission>pub async fn insert_exercise_slide_submission(
    conn: &mut PgConnection,
    exercise_slide_submission: NewExerciseSlideSubmission,
) -> ModelResult<ExerciseSlideSubmission>