collection:
  - title: "FOO"
    collection:
      - title: "Zoo"
        link: "zoo/"
      - title: "ZAM"
        link: "zam/"
  - title: "BAR"
    collection:
      - title: "Rad"
        link: "rad/"
      - title: "Goat"
        link: "goat/"


I'm looping over the above data-structure recursively each loop deals with a 'doc'
The first doc would be 'FOO'
   It would see that it has a 'collection' so call the function again etc.
   currentPage = File.join("/", File.dirname(current_page.path), File.basename(current_page.path, ".*"))

   How can I tell if the current doc child contains the currentPage