gistfile1.erb

   <div id="main">      
      <%= flash_notifications %>
      <div id="heading">
        <%= yield :heading %>
        <div class="clear_both">
        </div>
      </div>
      <% if yield(:left_column) && yield(:right_column) %>
        <div class="left_column">
          <%= yield :left_column %>
        </div>
        <div class="right_column">
          <%= yield :right_column %>
        </div>
        <div class="clear_both">
        </div>
      <% end %>
      <%= yield %>
    </div>