code: def __call__(self, input, target):
      loss_fct = torch.nn.CrossEntropyLoss(ignore_index=-1)
      loss = loss_fct(input.view(-1, input.size(-1)), target.view(-1))
      return loss
  
imports: import torch
  from pytorch_pretrained_bert import BertTokenizer
  from transfer_nlp.plugins.config import register_plugin
label_desc: Use image node_id 1 for calling the FineTuningLoss obj's underlying member method code with example usage: obj.__call__(input, target) and returns: loss