class_docstr: analogous to fairseq.data.IndexedCachedDataset
code: def __len__(self):
      # offsets includes 0 and end indices for each example
      return self.word_offsets.size - 1
  
imports: from typing import Any, Dict
  import numpy
  import torch
  from fairseq import data, tokenizer
  from fvcore.common.file_io import PathManager
  from pytorch_translate import vocab_constants
  from pytorch_translate.data.dictionary import TAGS
label_desc: Use image node_id 4 for calling the InMemoryNumpyWordCharDataset obj's underlying member method code with example usage: obj.__len__() and returns: unknown