docstr: Helper function for the cross entropy.
docstr_tok: ["Helper","function","for","the","cross","entropy","."]
code: def forward(self, vocab_parallel_logits, target):
      """Helper function for the cross entropy."""
      vocab_parallel_logits = vocab_parallel_logits[
          ..., :-1, :
      ].contiguous()
      target = target[..., 1:].contiguous()
      return _VocabParallelCrossEntropy.apply(
          vocab_parallel_logits.view(
              -1, vocab_parallel_logits.size(-1)
          ),
          target.view(-1),
      )
  
imports: import torch
  import torch.nn.init
  from torch import Tensor
  from torch import nn
  from torch.nn import functional
  from torch.nn.parameter import Parameter
  from colossalai.legacy.context import ParallelMode, seed
  from colossalai.legacy.core import global_context
  from colossalai.legacy.nn.layer.base_layer import ParallelLayer
  from colossalai.legacy.nn.layer.parallel_1d._utils import gather_forward_split_backward, reduce_grad, reduce_input
  from colossalai.legacy.nn.layer.parallel_1d.layers import Linear1D_Row
  from colossalai.legacy.nn.layer.utils import divide
  from colossalai.legacy.registry import LAYERS, LOSSES
  from colossalai.utils import get_current_device
label_desc: Use image node_id 2 for calling the vocab_parallel_cross_entropy obj's underlying member method code with example usage: obj.forward(vocab_parallel_logits, target) and returns: _VocabParallelCrossEntropy