code: def tree(root_depth: 1, sitemap: false, nav_class: 'tree')
        return if m.parent_at_depth(root_depth).nil?
        @sitemap = sitemap
        h.content_tag :nav, class: nav_class do
          h.concat render_tree_master_ul(m.parent_at_depth(root_depth))
        end
      end
docs: build page tree from specified root_depth, default second level root with sitemap property to render a sitemap from top root of current page