pub async fn create_exam(
    conn: &mut PgConnection,
    name: String,
    starts_at: Option<DateTime<Utc>>,
    ends_at: Option<DateTime<Utc>>,
    time_minutes: i32,
    organization_id: Uuid,
    course_id: Uuid,
    exam_id: Uuid,
    teacher: Uuid,
    minimum_points_treshold: i32,
    base_url: String,
    jwt_key: Arc<JwtKey>
) -> Result<Uuid>