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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 batch(self, batch_obj):
 """ Set a batch object to run the query on. Note: running a select query with a batch object will raise an exception """

        if self._connection:
            raise CQLEngineException("Cannot specify the connection on model in batch mode.")

        if batch_obj is not None and not isinstance(batch_obj, BatchQuery):
            raise CQLEngineException('batch_obj must be a BatchQuery instance or None')
        clone = copy.deepcopy(self)
        clone._batch = batch_obj
        return clone