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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_node_attribute(self, node, attr):
 """ Add attribute to the given node. @type node: node @param node: Node identifier @type attr: tuple @param attr: Node attribute specified as a tuple in the form (attribute, value). """

        self.node_attr[node] = self.node_attr[node] + [attr]