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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 mll(y_true, y_pred, y_var):
 """ Mean log loss under a Gaussian distribution. Parameters y_true: ndarray vector of true targets y_pred: ndarray vector of predicted targets y_var: float or ndarray predicted variances Returns ------- float: The mean negative log loss (negative log likelihood) Example ------- True True """


    return - norm.logpdf(y_true, loc=y_pred, scale=np.sqrt(y_var)).mean()