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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(self, node):
 """Add Node, replace existing node if node with node_id is present."""

        if not isinstance(node, Node):
            raise TypeError()
        for i, j in enumerate(self.__nodes):
            if j.node_id == node.node_id:
                self.__nodes[i] = node
                return
        self.__nodes.append(node)