docstr: Test that to_np with margin=0 cuts the last observation.
code: def test_trajectory_to_np_without_margin_cuts_last_observation(self):
      """Test that to_np with margin=0 cuts the last observation."""
      tr = rl_task.Trajectory(observation=0)
      for obs in range(1, 4):
          self._extend(tr, new_observation=obs)
      tr_np = tr.to_np(margin=0)
      np.testing.assert_array_equal(tr_np.observation, [0, 1, 2])
  
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 13 for calling the TaskTest obj's underlying member method code with example usage: obj.test_trajectory_to_np_without_margin_cuts_last_observation() without return types