re, numbers are sorted by their values, and come before all strings.
    An omitted `nav_order` value is equivalent to the page's `title` value
    (except that a numerical `title` value is treated as a string).

    The case-sensitivity of string sorting is determined by `site.nav_sort`.
  {%- endcomment -%}
  
  {%- assign string_ordered_pages = titled_pages
        | where_exp:"item", "item.nav_order == nil" -%}
  {%- assign nav_ordered_pages = titled_pages
        | where_exp:"item", "item.nav_order != 