anchor.diff:  
   <table>
   
  -  <%= yield :table_headers %>
  +  <%= yield yield_name %>
   
     <% items.each do |item| %>
       <tr class="<%= cycle('even', 'odd') %>" id="<%= dom_id(item) %>">
  
positive.code: <% content_for :table_headers do %>
    <thead>
      <tr>
        <% if controller.respond_to?(:bulk) %>
  
negative.code:     </tr>
    <% end %>
  
    <%= yield yield_name %>
  
  </table>
  