Had the folder misplacement of file didn't run the code? I'll check and update it ASAP. Sorry for the confusion.
You mentioned: "We are going to place both functions in a separate module organization.ex under trello_app/lib/trello_app folder." I suppose it to be in trello_app/lib folder because:
- The name of the created module you were displaying later was defmodule TrelloApp.Organization
- you asked to alias it as TrelloApp.Organization later in the iex session.