Applying https://www.jamesshore.com/v2/projects/nullables to Elixir.
git clone https://github.com/nicholasjhenry/testing-without-mocks-example.git
mix test
Command line:
script/rot13 hello
# => uryyb
Server:
script/server 4001
# New terminal
brew install httpie
http http://localhost:4001/rot13/transform text=world
# => { "transform": "uryyb" }