title: Shared code in umbrella app
body: <p>I have the following directory structure for my umbrella app :</p>
  
  <pre><code>umbrella_app/
      _build/
      apps/
        client/
           config/
           lib/
             client.ex
           test/
         server/
           ...
      config/
  </code></pre>
  
  <p>Is there a way I can write code somewhere inside <code>umbrella_app</code> that will be accessible from both my <code>client</code> and <code>server</code> without creating another child app ?</p>
  
  <p>Such as :</p>
  
  <pre><code># umbrella_app/apps/client/lib/client.ex
  
  defmodule UmbrellaApp.Client do
    UmbrellaApp.some_function()
  end
  </code></pre>