


loss = nn.MultiMarginLoss()
      >>> x = torch.tensor([[0.1, 0.2, 0.4, 0.8]])
      >>> y = torch.tensor([3])
      >>> # 0.25 * ((1-(0.8-0.1)) + (1-(0.8-0.2)) + (1-(0.8-0.4)))
      >>> loss(x, y)
      tensor(0.32...)


