class_docstr: Evaluation Dataset class.
  Parameters
  ----------
  triples: The triples used for evaluating the model
  num_ent: Number of entities in the knowledge graph
  
  Returns
  -------
  An evaluation Dataset class instance used by DataLoader for model evaluation
code: def __len__(self):
      return len(self.triples)
  
imports: from collections import defaultdict
  import dgl
  import numpy
  import torch
  from ordered_set import OrderedSet
  from torch.utils.data import DataLoader, Dataset
label_desc: Use image node_id 2 for calling the TestDataset obj's underlying member method code with example usage: obj.__len__() and returns: len