code: def __len__(self):
      return len(self.batch_list)
  
file_path: espnet/espnet2/samplers/num_elements_batch_sampler.py
imports: from typing import Iterator, List, Tuple, Union
  import numpy
  from typeguard import check_argument_types
  from espnet2.fileio.read_text import load_num_sequence_text
  from espnet2.samplers.abs_sampler import AbsSampler
label_desc: Use image node_id 3 for calling the NumElementsBatchSampler obj's underlying member method code with example usage: obj.__len__() and returns: len