title: Rails Tutorial Chapter 4 2nd Ed. Title Helper not being called with out argument
body: <p>I am running through the Rails Tutorial by Michael Hartl (Screen Cast). Ran into the and issue in chapter 4 on the title helper. </p>
  
  <p>I have been putting my own twist on the code as I go to make sure I understand it all. However on this one I it is very similar and I am not quite sure why it is acting the way it is. </p>
  
  <p>Here is the code:</p>
  
  <p>Application.html.erb</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
    &lt;head&gt;
      &lt;%- Rails.logger.info("Testing: #{yield(:title)}") %&gt;
      &lt;title&gt;&lt;%= full_title(yield(:title)) %&gt;&lt;/title&gt;
      &lt;%= stylesheet_link_tag    "application", :media =&gt; "all" %&gt;
      &lt;%= javascript_include_tag "application" %&gt;
      &lt;%= csrf_meta_tags %&gt;
    &lt;/head&gt;
    &lt;body&gt;
      &lt;%= yield %&gt;
    &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>Application_helper.rb</p>
  
  <pre><code>module ApplicationHelper
    def full_title(page_title)
      full_title = "Ruby on Rails Tutorial App"
      full_title += " | #{page_title}" unless page_title.blank?
    end
  end
  </code></pre>
  
  <p>Home.html.erb</p>
  
  <pre><code>&lt;h1&gt;&lt;%= t(:sample_app) %&gt;&lt;/h1&gt;
  &lt;p&gt;
    This is the home page for the &lt;a href="http://railstutorial.org/"&gt;Ruby on Rails Tutorial&lt;/a&gt; sample application
  &lt;/p&gt;
  </code></pre>
  
  <p>about.html.erb</p>
  
  <pre><code> &lt;% provide(:title, t(:about_us)) %&gt;
   &lt;h1&gt;&lt;%= t(:about_us) %&gt;&lt;/h1&gt;
   &lt;p&gt;
     The &lt;a href="http://railstutorial.org/"&gt;Ruby on Rails Tutorial&lt;/a&gt; is a project to make a book and screencast to teach web development with &lt;a href="http://railstutorial.org/"&gt;Ruby on Rails&lt;/a&gt;. This is the sample application for the tutorial.
   &lt;/p&gt;
  </code></pre>
  
  <p>What Happens: The code works fine when I set the provide method like on the about page. However when I do not it does not seem to even call the helper. I am assuming that because no title is passed back. Any ideas on what I am doing wrong? </p>
  
  <p>Thank you all for your help.</p>
  
  <p>Edit:
  This is the fix. Thanks to Paul for pointing out that the last line was returning nothing and was why my code was not working. Changed it so it return something not mater the case. </p>
  
  <p>Application_helper.rb</p>
  
  <pre><code>module ApplicationHelper
    def full_title(page_title)
      full_title = "Ruby on Rails Tutorial App"
      page_title.present? ? (full_title += " | #{page_title}") : full_title
    end
  end
  </code></pre>