code: def test_predict(self):
      with torch.no_grad():
          feat_maps = torch.zeros((1, 10, 128, 128))
          self.drrg_head.out_conv.bias.data.fill_(-10)
          preds = self.drrg_head(feat_maps)
          self.assertTrue(all([pred is None for pred in preds]))
  
imports: from unittest import TestCase, mock
  import numpy
  import torch
  from mmocr.models.textdet.heads.drrg_head import GCN, DRRGHead, LocalGraphs, ProposalLocalGraphs, feature_embedding, normalize_adjacent_matrix
label_desc: Use image node_id 3 for calling the TestDRRGHead obj's underlying member method code with example usage: obj.test_predict() without return types