code: def test_certainty(distributions, reduction):
      np.random.seed(1337)
      certainty = Certainty(reduction=reduction)
      marg = certainty(distributions)
      assert np.all(
          marg == [1, 2, 0]
      ), "Certainty is not right {}".format(marg)
  
      certainty = Certainty(0.9, reduction=reduction)
      marg = certainty(distributions)
      assert np.any(marg != [1, 2, 0])
  
imports: import warnings
  import numpy
  import pytest
  from hypothesis import given
  from torch_hypothesis import class_logits
  from baal.active import get_heuristic
  from baal.active.heuristics import Random, BALD, Margin, Entropy, Certainty, Variance, BatchBALD, AbstractHeuristic, requireprobs, Precomputed, CombineHeuristics
  from tests.test_utils import make_fake_dist, make_3d_fake_dist, make_5d_fake_dist
label_desc: Use image node_id 8 for calling a global function with example usage: test_certainty(distributions, reduction) without return types