code: def forward(self, pos_graph, neg_graph, blocks):
      h_item = self.get_repr(blocks)
      pos_score = self.scorer(pos_graph, h_item)
      neg_score = self.scorer(neg_graph, h_item)
      return (neg_score - pos_score + 1).clamp(min=0)
  
imports: import argparse
  import os
  import pickle
  import dgl
  import evaluation
  import layers
  import numpy
  import sampler
  import torch
  import torch.nn
  import torchtext
  import tqdm
  from torch.utils.data import DataLoader
  from torchtext.data.utils import get_tokenizer
  from torchtext.vocab import build_vocab_from_iterator
label_desc: Use image node_id 2 for calling the PinSAGEModel obj's underlying member method code with example usage: obj.forward(pos_graph, neg_graph, blocks) and returns: unknown