todo
  Task
    DEFAULT_PRIORITY
    title
    description
    done
    priority
    complete(self)
    reset(self)
    classmethod urgent(cls, title)
    staticmethod is_valid_title(title)
  TodoList
    name
    count (property)
    add(self, task)
    remove(self, title)
    pending(self)
    complete_all(self)
  from_lines(lines)
