def item(key, name, url = nil, options = {}, &block)
      return unless should_add_item?(options)
      item = Item.new(self, key, name, url, options, &block)
      add_item item, options
    end
def item(key, name, url = nil, options = {}, &block)
      return unless should_add_item?(options)
      item = Item.new(self, key, name, url, options, &block)
      add_item item, options
    end
Creates a new navigation item.

 The <tt>key</tt> is a symbol which uniquely defines your navigation item
 in the scope of the primary_navigation or the sub_navigation.

 The <tt>name</tt> will be displayed in the rendered navigation.
 This can also be a call to your I18n-framework.

 The <tt>url</tt> is the address that the generated item points to.
 You can also use url_helpers (named routes, restful routes helper,
 url_for, etc). <tt>url</tt> is optional - items without URLs should not
 be rendered as links.

 The <tt>options</tt> can be used to specify the following things:
 * <tt>any html_attributes</tt> - will be included in the rendered
   navigation item (e.g. id, class etc.)
 * <tt>:if</tt> - Specifies a proc to call to determine if the item should
   be rendered (e.g. <tt>if: Proc.new { current_user.admin? }</tt>). The
   proc should evaluate to a true or false value and is evaluated
   in the context of the view.
 * <tt>:unless</tt> - Specifies a proc to call to determine if the item
   should not be rendered
   (e.g. <tt>unless: Proc.new { current_user.admin? }</tt>).
   The proc should evaluate to a true or false value and is evaluated in
   the context of the view.
 * <tt>:method</tt> - Specifies the http-method for the generated link -
   default is :get.
 * <tt>:highlights_on</tt> - if autohighlighting is turned off and/or you
   want to explicitly specify when the item should be highlighted, you can
   set a regexp which is matched againstthe current URI.

 The <tt>block</tt> - if specified - will hold the item's sub_navigation.