code: def create_id2collection_info(path, tag):
      
      d = {}
      for triple in os.walk(path):
          root, files = triple[0], triple[2]
          for filename in files:
              if filename.endswith('.json'):
                  # trim file extension and prepend owner_id (from path)
                  collection_id = "{u}/{n}".format(u=root.split('/')[-1], n=filename[:-5])
                  d[collection_id] = (tag, root, os.path.join(root, filename))
      return d
docs: Searchers for JSON files in this repo and returns
      a map of collection id ==> (`tag`, dir, collection filepath)
      where `tag` is typically the shard name