class_docstr: Return (hash(origin_sample), origin_sample).
  
  Parameters
  ----------
  hash_fn
      A hash function of sample from dataset, the hash value should be a str.
class_docstr_tok: ["Return","(","hash","(","origin_sample",")",",","origin_sample",")",".","Parameters","--","--","--","--","--","hash_fn","A","hash","function","of","sample","from","dataset",",","the","hash","value","should","be","a","str","."]
code: def __getitem__(self, index):
      sample = self._dataset.__getitem__(index)
      return self._hash_fn(sample), sample
  
imports: from __future__ import annotations
  from collections import defaultdict
  from typing import Any, Callable, Dict, List, Type
  import torch
  from torch.utils.data import Dataset, IterableDataset
  from .utils import _default_get_rngs_state, _default_set_rngs_state, _default_manual_seed
label_desc: Use image node_id 2 for calling the HashedDataset obj's underlying member method code with example usage: obj.__getitem__(index) and returns: self,  sample