code: def test_significance_map(self):
      np.testing.assert_array_equal(
          self._serializer.significance_map, [0, 0]
      )
  
imports: import gin
  import gym
  import numpy
  from tensorflow import test
  from trax.rl import space_serializer
label_desc: Use image node_id 6 for calling the MultiDiscreteSpaceSerializerTest obj's underlying member method code with example usage: obj.test_significance_map() without return types