notebook.community
Edit and run
https://try.github.io/levels/1/challenges/1
https://www.youtube.com/watch?v=1ffBJ4sVUb4
http://pcottle.github.io/learnGitBranching
http://nvie.com/posts/a-successful-git-branching-model/
https://git-scm.com/book/en/v2
https://github.com/pluralsight/git-internals-pdf