code: def lookup_index(self, chunk_i, i):
      if isinstance(i, (int, np.ndarray, torch.Tensor)):
          return chunk_i * self.chunk_size + i
      else:
          raise TypeError(type(i))
  
imports: import math
  import numpy
  import os
  from typing import Generator, Union, Sequence
  import torch
  import torch.utils.data.dataset
label_desc: Use image node_id 5 for calling the Chunker obj's underlying member method code with example usage: obj.lookup_index(chunk_i, i) and returns: unknown