code: def _find_by_name(tree_data, name, is_dir, start_at):
      
      try:
          item = tree_data[start_at]
          if item and item[2] == name and S_ISDIR(item[1]) == is_dir:
              tree_data[start_at] = None
              return item
      except IndexError:
          pass
      # END exception handling
      for index, item in enumerate(tree_data):
          if item and item[2] == name and S_ISDIR(item[1]) == is_dir:
              tree_data[index] = None
              return item
          # END if item matches
      # END for each item
      return None
docs: return data entry matching the given name and tree mode
      or None.
      Before the item is returned, the respective data item is set
      None in the tree_data list to mark it done