class_docstr: Subset of a dataset at specified indices.
  
  Args:
      dataset (Dataset): The whole Dataset
      indices (sequence): Indices in the whole set selected for subset
class_docstr_tok: ["Subset","of","a","dataset","at","specified","indices",".","Args",":","dataset","(","Dataset",")",":","The","whole","Dataset","indices","(","sequence",")",":","Indices","in","the","whole","set","selected","for","subset"]
code: def __len__(self):
      return len(self.indices)
  
imports: import sys
  import os
  import random
  import pgl
  from pgl.utils.logger import log
  from pgl.graph import Graph, MultiGraph
  import numpy
  import pickle
label_desc: Use image node_id 3 for calling the Subset obj's underlying member method code with example usage: obj.__len__() and returns: len