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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 log_likelihood(self):
 """ Notice we add the jacobian of the warping function here. """

        ll = GP.log_likelihood(self)
        jacobian = self.warping_function.fgrad_y(self.Y_untransformed)
        return ll + np.log(jacobian).sum()