code: def __len__(self) -> int:
      return len(self.modules)
  
imports: from collections import OrderedDict
  from dataclasses import dataclass, field
  import itertools
  import threading
  from typing import TYPE_CHECKING, Any, Dict, Iterable, List, Optional, Tuple, Union
  import warnings
  import torch
  from torch import Tensor, nn
  from fairscale.nn.model_parallel import get_pipeline_parallel_group
  from .None import microbatch
  from .async_pipeline import AsyncPipeline
  from .async_schedule import Invocation, Location, ModuleWrapper
  from .batchnorm import DeferredBatchNorm
  from .skip.layout import SkipLayout
  from .skip.skippable import Skippable
  from .types import LazyModule
label_desc: Use image node_id 1 for calling the PartitionInfo obj's underlying member method code with example usage: obj.__len__() and returns: len