Hi @Margaret ,
On page VII the book tells us the example and snippets will be all using Elixir version 1.11
But on page 3 almost the end of the page when has a print of the IEx console, the version of the Elixir is 1.9.4 instead of 1.11.
So and the most part of the book suggest use the recompile function on IEx, but sometimes after you change your code you continue to receive :noop on IEx, maybe change the approach to use the r function, e.g., r(Sender), will be more efficient, using this way I tell recompile the Sender module on my application and no matter what if I change my code or not.