The text here could do with more explanation. It assumes a considerable amount of knowledge outside that covered so far in the book. If a reader doesn’t have this additional knowledge, they will not be able to understand what is being said here - which is pretty key to what we’re about to do.

an example of what I’m referring to:

“…The configuration sets the default adapter, PubSub.PG2. This adapter runs on Distributed Erlang––clients across distributed nodes of our app can subscribe to a shared topic and broadcast to that shared topic, because PubSub can directly exchange notifications between servers when configured to use the Phoenix.PubSub.PG2 adapter…”