class_docstr: Used by split_dataset
class_docstr_tok: ["Used","by","split_dataset"]
code: def __len__(self):
      return len(self.keys)
  
imports: import hashlib
  import operator
  import sys
  from collections import Counter
  from collections import OrderedDict
  from datetime import datetime
  from numbers import Number
  import numpy
  import torch
label_desc: Use image node_id 3 for calling the _SplitDataset obj's underlying member method code with example usage: obj.__len__() and returns: len