I've written ebuild files for Nikola (a static website builder). Because Gentoo's official portage doesn't provide Nikola-7.0.0-ebuild.
Many ebuild files are necesary because of its dependency. Almost all of them are python programs.
In wjn-overlay, www-apps/nikola and dev-python/* are them.
My nikola-7.0.0.ebuild has many USE flags. If all enabled, it will be equal to do 'pip nikola[extras]'. But ipython has heavy dependency. So, if unneccesary I recommend to do "-ipython".