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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 metric(self):
 """ The metric of the parameter space. This is a Dictionary of numpy.matrix Each entry in the dictionary is as described under evals. Each numpy.matrix contains the metric of the parameter space in the Lambda_i coordinate system. """

        if self._metric is None:
            errMsg = "The metric eigenvectors have not been set in the "
            errMsg += "metricParameters instance."
            raise ValueError(errMsg)
        return self._metric