code: def __call__(self, batch_data):
      src_list = []
      pos_list = []
      for src, pos in batch_data:
          src_list.append(src)
          pos_list.append(pos)
  
      src_list = np.array(src_list, dtype="int64").reshape(-1, 1)
      pos_list = np.array(pos_list, dtype="int64").reshape(-1, 1)
      return {"src": src_list, "pos": pos_list}
  
imports: import os
  import sys
  import time
  import warnings
  import numpy
  from collections import defaultdict
  from pgl.graph_kernel import skip_gram_gen_pair
  from pgl.utils.logger import log
  from pgl.distributed import DistGraphClient, DistGraphServer
  from pgl.utils.data import Dataloader, StreamDataset
  from utils.config import prepare_config
  from datasets.node import NodeGenerator
  from datasets.walk import WalkGenerator
  from datasets.pair import PairGenerator
label_desc: Use image node_id 2 for calling the CollateFn obj's underlying member method code with example usage: obj.__call__(batch_data) and returns: dict