code: def test_product_rule():
      expected = 2
      result = product_rule(example_kuncheva_batch)
      assert np.allclose(expected, result)
  
imports: import pytest
  from deslib.util.aggregation import *
  from ..conftest import create_base_classifier
label_desc: Use image node_id 13 for calling a global function with example usage: test_product_rule() without return types