https://llis.nasa.gov/lesson/1956

https://beta.observablehq.com/@mbostock/comma-separated-tree

https://medium.freecodecamp.org/distributed-systems-when-you-should-build-them-and-how-to-scale-a-step-by-step-guide-37e76a177218

https://twitter.com/math_rachel/status/1069719443239038976

https://cosmicbboy.github.io/2018/12/28/validating-pandas-dataframes.html

https://thenextweb.com/dd/2019/01/05/github-now-gives-free-users-unlimited-private-repositories/

https://twitter.com/ivomagi/status/1067527108518383622