part 1.1: https://www.mediafactory.org.au/shijie-luo/2019/04/27/assignment2-part-1-1/
part 1.2: https://www.mediafactory.org.au/shijie-luo/2019/04/27/part-1-2/
part 2 : https://www.mediafactory.org.au/shijie-luo/2019/04/27/part-2/
part 3 : https://www.mediafactory.org.au/shijie-luo/2019/04/29/part-3-2/
part 4 : https://www.mediafactory.org.au/shijie-luo/2019/04/27/part-4/