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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 _get_loss_fn(self):
 """Returns the loss function to use in the train_model routine"""

        criteria = self.criteria.to(self.config["device"])
        loss_fn = lambda X, Y: sum(
            criteria(Y_tp, Y_t) for Y_tp, Y_t in zip(self.forward(X), Y)
        )
        return loss_fn