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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 onMessage(self, client, userdata, msg):
 """! The callback for when a PUBLISH message is received from the server. @param client @param userdata @param msg """

        dataIdentifier = DataIdentifier(self.broker, msg.topic)
        self.dataHandler.onNewData(dataIdentifier, msg.payload)