    # File lib/chef/resource.rb, line 181
        def self.identity_attr(attr_name=nil)
          @identity_attr ||= nil
          @identity_attr = attr_name if attr_name

          # If this class doesn't have an identity attr, we'll defer to the superclass:
          if @identity_attr || !superclass.respond_to?(:identity_attr)
            @identity_attr
          else
            superclass.identity_attr
          end
        end