code: def __len__(self):
      return (self._size - self._start + self._step - 1) // self._step
  
imports: import itertools
  from typing import Any, Optional
  import warnings
  import numpy
  import torch
  from torch.utils.data.sampler import Sampler
  import dinov2.distributed
label_desc: Use image node_id 3 for calling the EpochSampler obj's underlying member method code with example usage: obj.__len__() and returns: unknown