code: def __init__(self, g, num_rels, sample_size=30000, num_epochs=6000):
      self.g = g
      self.num_rels = num_rels
      self.sample_size = sample_size
      self.num_epochs = num_epochs
      self.pos_sampler = GlobalUniform(g, sample_size)
      self.neg_sampler = NegativeSampler()
  
imports: import dgl
  import numpy
  import torch
  import torch.nn
  import torch.nn.functional
  import tqdm
  from dgl.data.knowledge_graph import FB15k237Dataset
  from dgl.dataloading import GraphDataLoader
  from dgl.nn.pytorch import RelGraphConv
label_desc: Use image node_id 1 to create a new SubgraphIterator object  with example: obj = SubgraphIterator(g, num_rels, sample_size, num_epochs)