class_docstr: Base class for callback.
  
  :param verbose: (int)
class_docstr_tok: ["Base","class","for","callback",".",":","param","verbose",":","(","int",")"]
code: def __init__(self, verbose: int = 0):
      super(BaseCallback, self).__init__()
      # The RL model
      self.model = None  # type: Optional[BaseRLModel]
      # An alias for self.model.get_env(), the environment used for training
      self.training_env = None  # type: Union[gym.Env, VecEnv, None]
      # Number of time the callback was called
      self.n_calls = 0  # type: int
      # n_envs * n times env.step() was called
      self.num_timesteps = 0  # type: int
      self.verbose = verbose
      self.locals = None  # type: Optional[Dict[str, Any]]
      self.globals = None  # type: Optional[Dict[str, Any]]
      self.logger = None  # type: Optional[logger.Logger]
      # Sometimes, for event callback, it is useful
      # to have access to the parent object
      self.parent = None
  
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 1 to create a new BaseCallback object from inherited base classes: ABC with example: obj = BaseCallback(verbose)