code: def test_representation_length(self):
      (space, serializer) = self._make_space_and_serializer()
      input_array = self._sample_batch(space)
      representation = serializer.serialize(input_array)
      self.assertEqual(
          representation.shape, (1, serializer.representation_length)
      )
  
imports: import gin
  import gym
  import numpy
  from tensorflow import test
  from trax.rl import space_serializer
label_desc: Use image node_id 3 for calling the BoxSpaceSerializerTest obj's underlying member method code with example usage: obj.test_representation_length() without return types