_default_layout

# File actionview/lib/action_view/layouts.rb, line 412
    def _default_layout(lookup_context, formats, require_layout = false)
      begin
        value = _layout(lookup_context, formats) if action_has_layout?
      rescue NameError => e
        raise e, "Could not render layout: #{e.message}"
      end

      if require_layout && action_has_layout? && !value
        raise ArgumentError,
          "There was no default layout for #{self.class} in #{view_paths.inspect}"
      end

      _normalize_layout(value)
    end