Factory function for envs.

def make_env(env_type, real_env, sim_env_kwargs):
  """Factory function for envs."""
  return {
      "real": lambda: real_env.new_like(  # pylint: disable=g-long-lambda
          batch_size=sim_env_kwargs["batch_size"],
          store_rollouts=False,
      ),
      "simulated": lambda: rl_utils.SimulatedBatchGymEnvWithFixedInitialFrames(  # pylint: disable=g-long-lambda
          **sim_env_kwargs
      ),
  }[env_type]()