https://www.r-bloggers.com/in-depth-introduction-to-machine-learning-in-15-hours-of-expert-videos/
https://raw.githubusercontent.com/asadoughi/stat-learning/master/ch2/answers
http://www-bcf.usc.edu/~gareth/ISL/
What I see in different shades of gray, from behind my reading glasses
https://www.r-bloggers.com/in-depth-introduction-to-machine-learning-in-15-hours-of-expert-videos/
https://raw.githubusercontent.com/asadoughi/stat-learning/master/ch2/answers
http://www-bcf.usc.edu/~gareth/ISL/