code: def forward(self, logits, labels):
      shift_logits = logits[..., :-1, :].contiguous()
      shift_labels = labels[..., 1:].contiguous()
      # Flatten the tokens
      return self.loss_fn(
          shift_logits.view(-1, shift_logits.size(-1)),
          shift_labels.view(-1),
      )
  
imports: import argparse
  import os
  from contextlib import nullcontext
  from functools import partial
  from time import time
  import psutil
  import torch
  import torch.nn
  from commons.model_zoo import model_builder
  from commons.utils import get_data, get_profile_context, get_tflops, get_time_stamp
  from packaging import version
  import colossalai
  from colossalai.booster import Booster
  from colossalai.booster.plugin import GeminiPlugin, LowLevelZeroPlugin, TorchDDPPlugin
  from colossalai.lazy import LazyInitContext
  from colossalai.logging import disable_existing_loggers, get_dist_logger
  from colossalai.nn.optimizer import HybridAdam
  from colossalai.utils import get_current_device
label_desc: Use image node_id 2 for calling the GPTLMLoss obj's underlying member method code with example usage: obj.forward(logits, labels) and returns: self