docstr: Forward step.
docstr_tok: ["Forward","step","."]
code: def _fwd_step_func(self, batch, model):
      """Forward step."""
      (
          tokens,
          labels,
          loss_mask,
          attention_mask,
          position_ids,
      ) = self._get_batch(batch)
      output_tensor = model(
          tokens, position_ids, attention_mask, labels=labels
      )
      return output_tensor, partial(self._loss_func, loss_mask)
  
imports: from functools import partial
  from typing import List
  import time
  import torch
  import unittest
  from apex.transformer._ucc_util import HAS_UCC
  from apex.transformer import parallel_state
  from apex.transformer.enums import ModelType
  from apex.transformer.tensor_parallel import model_parallel_cuda_manual_seed
  from apex.transformer.pipeline_parallel.utils import average_losses_across_data_parallel_group, unwrap_model, setup_microbatch_calculator, get_ltor_masks_and_position_ids
  from apex.transformer.pipeline_parallel.schedules.common import _get_params_for_weight_decay_optimization, build_model
  from apex.transformer.pipeline_parallel.schedules.fwd_bwd_pipelining_without_interleaving import forward_backward_pipelining_without_interleaving
  from apex.transformer.testing.standalone_gpt import gpt_model_provider
  from apex.transformer.testing import global_vars
  from apex.transformer.testing.distributed_test_base import UccDistributedTestBase, NcclDistributedTestBase
  from torch.testing._internal import common_utils
  from torch.testing._internal.common_device_type import instantiate_device_type_tests
label_desc: Use image node_id 5 for calling the GptTestBase obj's underlying member method code with example usage: obj._fwd_step_func(batch, model) and returns: output_tensor,  partial