code: def __len__(self):
      return len(self.datasets[0])
  
file_path: fairseq/fairseq/data/concat_sentences_dataset.py
imports: import torch
  from .None import FairseqDataset
label_desc: Use image node_id 3 for calling the ConcatSentencesDataset obj's underlying member method code with example usage: obj.__len__() and returns: len