code: def __post_init__(self):
      if not isinstance(self.placements, tuple):
          self.placements = tuple(self.placements)
      self._hash: Optional[int] = None
  
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 1 for calling the DTensorSpec obj's underlying member method code with example usage: obj.__post_init__() without return types