    # File lib/facets/core/hash/variablize_keys.rb, line 23
      def variablize_keys!( of_class=nil )
        raise ArgumentError, "Parameter must be a class" unless of_class.kind_of?(Class) if of_class
        if of_class
          self.each_key do |k|
            if k.respond_to?(:to_s) and k.class == of_class
              k = k.to_s
              nk = k[0,1] != '@' ? k : "@#{k}"
              self[nk]=self.delete(k)
            end
          end
        else
          self.each_key do |k|
            if k.respond_to?(:to_s)
              k = k.to_s
              nk = k[0,1] != '@' ? k : "@#{k}"
              self[nk]=self.delete(k)
            end
          end
        end
        self
      end