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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 add_virtual_loss(self, up_to):
 """Propagate a virtual loss up to the root node. Args: up_to: The node to propagate until. (Keep track of this! You'll need it to reverse the virtual loss later.) """

        self.losses_applied += 1
        # This is a "win" for the current node; hence a loss for its parent node
        # who will be deciding whether to investigate this node again.
        loss = self.position.to_play
        self.W += loss
        if self.parent is None or self is up_to:
            return
        self.parent.add_virtual_loss(up_to)