title: <%= with a block in rails 4
body: <p>I'm trying to use a block in a helper,</p>
  <p>but that's giving me this error:</p>
  <pre><code>SyntaxError - syntax error, unexpected ')'
  ...rbout.concat(( green_title do ).to_s); _erbout.concat &quot;\n   ...
  ...                               ^
  (erb):4254: syntax error, unexpected end-of-input, expecting ')'
  ; _erbout.force_encoding(__ENCODING__)
                                        ^:
    (erb):1649:in `'
  </code></pre>
  <p>here's how I'm calling it:</p>
  <pre><code>  &lt;%= green_title do %&gt;
      text
    &lt;% end %&gt;
  </code></pre>
  <p>and here's my helper:</p>
  <pre><code>  def green_title(&amp;block)
      capture do 
        concat content_tag(:h3) do
          yeld
        end
      end 
    end
  </code></pre>