title: Slim Partial with Yield
body: <p>I have a Slim partial for a widget.  The widget has common elements and then some custom content that I want to yield to.  What's the correct syntax for that?  Here's what I thought would work, but doesn't.</p>
  
  <p>Widget Partial</p>
  
  <pre><code>.container
    .title= title
    .content
      == yield
  </code></pre>
  
  <p>Page</p>
  
  <pre><code>.page
    = render partial: "widget_partial", locals: { title: "Content 1" } do
      div Some really awesome content.
  
    = render partial: "widget_partial", locals: { title: "Content 2" } do
      span Different but also awesome content.
  </code></pre>