code: def __len__(self) -> int:
      raise NotImplementedError
  
file_path: espnet/espnet2/samplers/abs_sampler.py
imports: from abc import ABC, abstractmethod
  from typing import Iterator, Tuple
  from torch.utils.data import Sampler
label_desc: Use image node_id 1 for calling the AbsSampler obj's underlying member method code with example usage: obj.__len__() without return types