https://web.stanford.edu/class/cs25/
https://www.youtube.com/watch?v=mcep6W8oB1I https://www.youtube.com/watch?v=fz8wf9hN20c https://www.youtube.com/watch?v=wwQ1LQA3RCU https://www.youtube.com/watch?v=1GbDTTK3aR4 https://www.youtube.com/watch?v=ylEk1TE1uBo https://www.youtube.com/watch?v=mE7IDf2SmJg https://www.youtube.com/watch?v=ckNMsUuLryM