code: def collate_train(self, batches):
      heads, tails, neg_tails = batches[0]
      # Construct multilayer neighborhood via PinSAGE...
      (
          pos_graph,
          neg_graph,
          blocks,
      ) = self.sampler.sample_from_item_pairs(heads, tails, neg_tails)
      assign_features_to_blocks(
          blocks, self.g, self.textset, self.ntype
      )
  
      return pos_graph, neg_graph, blocks
  
imports: import dgl
  import numpy
  import torch
  from torch.utils.data import DataLoader, IterableDataset
  from torchtext.data.functional import numericalize_tokens_from_iterator
label_desc: Use image node_id 2 for calling the PinSAGECollator obj's underlying member method code with example usage: obj.collate_train(batches) and returns: pos_graph,  neg_graph,  blocks