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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 operator_complexity(self):
 """Operator complexity of this multigrid hierarchy. Defined as: Number of nonzeros in the matrix on all levels / Number of nonzeros in the matrix on the finest level """

        return sum([level.A.nnz for level in self.levels]) /\
            float(self.levels[0].A.nnz)