text: import torch.nn as nn
  import torch.nn.functional as F
  
  __author__ = "Sachin Mehta"
  __license__ = "GPL"
  __version__ = "1.0.1"
  __maintainer__ = "Sachin Mehta"
  
  
  class CrossEntropyLoss2d(nn.Module):
      '''
      This file defines a cross entropy loss for 2D images
      '''
      def __init__(self, weight=None):
          '''
          :param weight: 1D weight vector to deal with the class-imbalance
          '''
          super().__init__()
  
          self.loss = nn.NLLLoss2d(weight)
  
      def forward(self, outputs, targets):
          return self.loss(F.log_softmax(outputs, 1), targets)