code: def _unpad_tensor(
      self,
      tensor: torch.Tensor,
      pad_size: int,
  ) -> torch.Tensor:
      return tensor.narrow(
          self.dim,
          start=0,
          length=tensor.size(self.dim) - pad_size,
      )
  
imports: from dataclasses import dataclass
  from typing import Any, cast, List, NamedTuple, Optional, Tuple
  import torch
  import torch.distributed._functional_collectives
  import torch.distributed.distributed_c10d
  from torch.distributed._tensor._collective_utils import mesh_broadcast, mesh_scatter
  from torch.distributed.device_mesh import DeviceMesh
label_desc: Use image node_id 3 for calling the Shard obj's underlying member method code with example usage: obj._unpad_tensor(tensor, pad_size) and returns: tensor