Function prepare_refrences_for_test 

pub fn prepare_refrences_for_test(num: i32) -> HashMap<usize, HintReference>

Test helper: Create a HashMap of HintReferences for testing. Output: { 0: HintReference::new_simple(-num), 1: HintReference::new_simple(-num + 1), … num - 1: HintReference::new_simple(-1), num: HintReference::new_simple(0), }