class_docstr: Custom FX tracer for torchrec
  
  See `Torch.FX documentation <https://pytorch.org/docs/stable/fx.html>`_
  
  We create a custom FX tracer to trace torchrec based models. The custom tracer
  handles python generic types (i.e. NoWait[T], Awaitable[T]) and lower it to
  TorchScript if needed
code: def __init__(self, leaf_modules: Optional[List[str]] = None) -> None:
      super().__init__()
      self._leaf_modules: List[str] = (
          leaf_modules if leaf_modules is not None else []
      )
  
file_path: torchrec/torchrec/fx/tracer.py
imports: from typing import Any, Callable, Dict, List, Optional, Union
  import torch
  from torch.fx._compatibility import compatibility
  from torch.fx.graph import Graph
  from torch.fx.node import Argument
  from torchrec.distributed.types import LazyAwaitable, NoWait
  from torchrec.fx.utils import dmp_fx_trace_forward
label_desc: Use image node_id 1 to create a new Tracer object from inherited base classes: torch.fx with example: obj = Tracer(leaf_modules)