Suggestions

Dear Yuanyu

Thank you very much for your great support and kind explanation. It really helps me a lot. Regarding for suggestions 1, 2 and 4. I have already modified that and changed accordingly. As for your suggestion 3, I previously thought about that but I didn't add that because I want to maintain the code brevity and the detail explanation of the code has already been explained in the previous theory part. Thank you.

Regards Arthur