code: def load_and_train(algo_cfg: AlgorithmConfig, env: str, tmpdir):
      """Loads the checkpoint saved by save_and_train and trains for 2 iterations.
  
      Note: This function uses a seeded algorithm that can modify the global random state.
          Running it multiple times in the same process can affect other algorithms.
          Making it a Ray task runs it in a separate process and prevents it from
          affecting other algorithms' random state.
  
      Args:
          algo_cfg: The algorithm config to build the algo from.
          env: The gym genvironment to train on.
          tmpdir: The temporary directory to save the checkpoint to.
  
      Returns:
          The learner stats after 2 iterations of training.
  
      """
      algo_cfg = (
          algo_cfg.experimental(_enable_new_api_stack=True)
          .rollouts(num_rollout_workers=0)
          # setting min_time_s_per_iteration=0 and min_sample_timesteps_per_iteration=1
          # to make sure that we get results as soon as sampling/training is done at
          # least once
          .reporting(
              min_time_s_per_iteration=0,
              min_sample_timesteps_per_iteration=1,
          )
          .debugging(seed=10)
      )
      algo = algo_cfg.environment(env).build()
      tmpdir = str(tmpdir)
      algo.load_checkpoint(tmpdir)
      for _ in range(2):
          results = algo.train()
      return results["info"][LEARNER_INFO][DEFAULT_POLICY_ID]
  
file_path: ray/python/ray/rllib/tests/test_algorithm_save_load_checkpoint_learner.py
imports: import tempfile
  import unittest
  import ray
  from ray.rllib.algorithms.algorithm_config import AlgorithmConfig
  from ray.rllib.utils.test_utils import check, framework_iterator
  from ray.rllib.algorithms.ppo import PPOConfig
  from ray.rllib.policy.sample_batch import DEFAULT_POLICY_ID
  from ray.rllib.utils.metrics.learner_info import LEARNER_INFO
label_desc: Use image node_id 2 for calling a global function with example usage: load_and_train(algo_cfg, env, tmpdir) and returns: results