Loss Functions

nn.X                                  # where X is L1Loss, MSELoss, CrossEntropyLoss
                                      # CTCLoss, NLLLoss, PoissonNLLLoss,
                                      # KLDivLoss, BCELoss, BCEWithLogitsLoss,
                                      # MarginRankingLoss, HingeEmbeddingLoss,
                                      # MultiLabelMarginLoss, SmoothL1Loss,
                                      # SoftMarginLoss, MultiLabelSoftMarginLoss,
                                      # CosineEmbeddingLoss, MultiMarginLoss,
                                      # or TripletMarginLoss