def deferred_render(*args, &block)
      block_definition = builder.define(*args, &block)
      Blocks::BlockPlaceholder.new(block_definition)
    end
def deferred_render(*args, &block)
      block_definition = builder.define(*args, &block)
      Blocks::BlockPlaceholder.new(block_definition)
    end
TODO: this needs to be handled by a new renderer
  TODO: also get rid of BlockPlaceholder