docstr: Test that the shape of a to_np result matches the trajectory length.
code: def test_trajectory_to_np_shape(self):
      """Test that the shape of a to_np result matches the trajectory length."""
      tr = rl_task.Trajectory(observation=np.zeros((2, 3)))
      for _ in range(5):
          self._extend(tr, new_observation=np.zeros((2, 3)))
      tr_np = tr.to_np()
      self.assertEqual(tr_np.observation.shape, (len(tr), 2, 3))
      self.assertEqual(tr_np.action.shape, (len(tr),))
  
imports: import os
  from absl.testing import absltest
  import gym
  import numpy
  from trax import test_utils
  from trax.rl import task
label_desc: Use image node_id 9 for calling the TaskTest obj's underlying member method code with example usage: obj.test_trajectory_to_np_shape() without return types