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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 predict_y(self, Xnew):
 """ Compute the mean and variance of held-out data at the points Xnew """

        pred_f_mean, pred_f_var = self._build_predict(Xnew)
        return self.likelihood.predict_mean_and_var(pred_f_mean, pred_f_var)