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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 _update_from_pb(self, instance_pb):
 """Refresh self from the server-provided protobuf. Helper for :meth:`from_pb` and :meth:`reload`. """

        if not instance_pb.display_name:  # Simple field (string)
            raise ValueError("Instance protobuf does not contain display_name")
        self.display_name = instance_pb.display_name
        self.configuration_name = instance_pb.config
        self.node_count = instance_pb.node_count