text: import pickle
  import unittest
  
  from garage.envs.mujoco.hill.swimmer3d_hill_env import Swimmer3DHillEnv
  from tests.helpers import step_env
  
  
  class TestSwimmer3DHillEnv(unittest.TestCase):
      def test_pickleable(self):
          env = Swimmer3DHillEnv(regen_terrain=False)
          round_trip = pickle.loads(pickle.dumps(env))
          assert round_trip
          assert round_trip.difficulty == env.difficulty
          step_env(round_trip)
  
      def test_does_not_modify_action(self):
          env = Swimmer3DHillEnv(regen_terrain=False)
          a = env.action_space.sample()
          a_copy = a.copy()
          env.reset()
          env.step(a)
          self.assertEquals(a.all(), a_copy.all())
  