    # File lib/merb-core/controller/mixins/render.rb, line 523
      def append_content(obj, string = nil, &block)
        unless string || block_given?
          raise ArgumentError, "You must pass a block or a string into append_content"
        end
        @_caught_content[obj] = "" if @_caught_content[obj].nil?
        @_caught_content[obj] << string.to_s << (block_given? ? capture(&block) : "")
      end