code: def test_num_weights(self):
      assert self.model.num_weights() == 2**BIT_SIZE
  
imports: import os
  from pathlib import Path
  import vowpalwabbit
  from vowpalwabbit import Workspace
  import pytest
  import warnings
  import filecmp
label_desc: Use image node_id 4 for calling the TestVW obj's underlying member method code with example usage: obj.test_num_weights() without return types