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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 start_container(self):
 """Add a node to the tree that represents the start of a container. Until end_container is called, any nodes added through add_scalar_value or start_container will be children of this new node. """

        self.__container_lengths.append(self.current_container_length)
        self.current_container_length = 0
        new_container_node = _Node()
        self.__container_node.add_child(new_container_node)
        self.__container_nodes.append(self.__container_node)
        self.__container_node = new_container_node