class_docstr: Callback for saving a model every `save_freq` steps
  
  :param save_freq: (int)
  :param save_path: (str) Path to the folder where the model will be saved.
  :param name_prefix: (str) Common prefix to the saved models
class_docstr_tok: ["Callback","for","saving","a","model","every","`","save_freq","`","steps",":","param","save_freq",":","(","int",")",":","param","save_path",":","(","str",")","Path","to","the","folder","where","the","model","will","be","saved",".",":","param","name_prefix",":","(","str",")","Common","prefix","to","the","saved","models"]
code: def _init_callback(self) -> None:
      # Create folder if needed
      if self.save_path is not None:
          os.makedirs(self.save_path, exist_ok=True)
  
imports: import os
  from abc import ABC
  import warnings
  import typing
  from typing import Union, List, Dict, Any, Optional
  import gym
  import numpy
  from stable_baselines.common.vec_env import VecEnv, sync_envs_normalization, DummyVecEnv
  from stable_baselines.common.evaluation import evaluate_policy
  from stable_baselines import logger
label_desc: Use image node_id 2 for calling the CheckpointCallback obj's underlying member method code with example usage: obj._init_callback() without return types