docs: def add(self, name, priority=3, comment="", parent=""):
          """Adds new item to the model.
  
          Name argument may contain (ref:) syntax, which will be
          stripped down as needed.
  
          :parent: should have a form "<itemref>.<subitemref...>" (e.g. "1.1").
  
          :name: Name (with refs).
          :priority: Item's priority.
          :comment: Comment.
          :parent: Item's parent ("" for top-level item).
  
          """
          item = [name, priority, comment, False, []]
          data = self.data
          for c in self._split(parent):
              data = data[int(c) - 1][4]
          data.append(item)