In the finished book this won’t matter, but I was racking my brain as to why none of the Stream examples worked. The answer is that streams were added until 0.10 (released less than a week ago!) and
brew install elixir does not install that version.
Would’ve been nice to see a note in 8.2 that nothing in there will work unless you take steps not outlined on the website to install the latest version of elixir.