Rails flash messages using Twitter bootstrap 2

_flash.html.erb

<% [:notice, :error, :alert].each do |level| %>
    <% unless flash[level].blank? %>
        <div class="alert <%= flash_class(level) %>">
            <button type="button" class="close" data-dismiss="alert">&times;</button>
            <span><%= flash[level] %></span>
        </div>
    <% end %>
<% end %>

application_helper.rb

module ApplicationHelper
  def flash_class(level)
    case level
    when :notice then "info"
    when :error then "error"
    when :alert then "warning"
    end
  end
end