code: def _get_word_edge(self):
      word_window_freq, word_pair_count, windows_len = _get_windows(
          self.doc, self.window_size
      )
      pmi_edge_lst = _count_pmi(
          windows_len, word_pair_count, word_window_freq, self.threshold
      )
      for edge_item in pmi_edge_lst:
          word_indx1 = self.doc_node_num + self.word2id[edge_item[0]]
          word_indx2 = self.doc_node_num + self.word2id[edge_item[1]]
          if word_indx1 == word_indx2:
              continue
          self.graph.add_edge(
              word_indx1, word_indx2, weight=edge_item[2]
          )
  
imports: from collections import defaultdict
  import itertools
  import math
  import numpy
  from ..data_bundle import DataBundle
  from ..loader.classification import MRLoader, OhsumedLoader, R52Loader, R8Loader, NG20Loader
  from fastNLP.core.utils import f_rich_progress
label_desc: Use image node_id 3 for calling the GraphBuilderBase obj's underlying member method code with example usage: obj._get_word_edge() without return types