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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 count(self):
 """ Returns the number of rows matched by this query """

        if self._batch:
            raise CQLEngineException("Only inserts, updates, and deletes are available in batch mode")

        if self._result_cache is None:
            query = self._select_query()
            query.count = True
            result = self._execute(query)
            return result[0]['count']
        else:
            return len(self._result_cache)