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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 freeze_subjects(self):
 """Converts variable data into numpy arrays. This is required after all subjects have been added via the add_subject function, since we don't know ahead of time who is participating in the analysis due to various filtering possibilities. """

        self.phenotype_data = numpy.array(self.phenotype_data)
        self.covariate_data = numpy.array(self.covariate_data)