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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _active_todos(self):
 """ Returns a list of active todos, taking uncompleted subtodos into account. The stored length of the todolist is taken into account, to prevent new todos created by recurrence to pop up as newly activated tasks. Since these todos pop up at the end of the list, we cut off the list just before that point. """

        return [todo for todo in self.todolist.todos()
                if not self._uncompleted_children(todo) and todo.is_active()]