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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 node_pairing(self):
 """if "node" then test current node and next one if "tag", then create tests for every pair of the current tag. """

        value = self.attributes['node_pairing']
        if value not in IMB.NODE_PAIRING:
            msg = 'Unexpected {0} value: got "{1}" but valid values are {2}'
            msg = msg.format('node_pairing', value, IMB.NODE_PAIRING)
            raise ValueError(msg)
        return value