https://www.digitalocean.com/community/tutorials/how-to-create-a-pull-request-on-github
https://www.atlassian.com/blog/git/alternatives-to-git-submodule-git-subtree
https://www.youtube.com/watch?v=0fKg7e37bQE&index=14&list=PLoYCgNOIyGAB_8_iq1cL8MVeun7cB6eNc
https://www.youtube.com/watch?v=oFYyTZwMyAg&list=PLoYCgNOIyGAB_8_iq1cL8MVeun7cB6eNc&index=15