code: def __len__(self):
      if self.max_num_samples is None:
          return len(self.indexed_dataset)
      else:
          return len(self.samples_mapping)
  
file_path: NeMo/nemo/collections/nlp/data/language_modeling/t0_dataset.py
imports: import numpy
  import torch
  from nemo.collections.common.tokenizers.tokenizer_spec import TokenizerSpec
  from nemo.collections.nlp.data.language_modeling.megatron.dataset_utils import get_samples_mapping
  from nemo.collections.nlp.data.language_modeling.text_memmap_dataset import JSONLMemMapDataset, TextMemMapDataset
  from nemo.core.classes import Dataset
label_desc: Use image node_id 3 for calling the T0Dataset obj's underlying member method code with example usage: obj.__len__() and returns: len, len