code: def get_bool_env_variable(
      variable_name: str, default_variable_value: bool
  ) -> bool:
      """Fetch bool value stored in environment variable.
  
      If environment variable is set but value is
      not of boolean nature, an exception will be raised.
  
      Args: variable_name:
          Name of the environment variable.
          default_variable_value: Value to be returned if environment variable is not set.
  
      Returns:
          A boolean value stored in the environment variable
          or default value if environment variable is not set.
      """
      true_values = (str(True).lower(), str(1).lower())
      false_values = (str(False).lower(), str(0).lower())
      value = os.getenv(
          variable_name, default=str(default_variable_value)
      )
  
      if value.lower() not in true_values + false_values:
          raise RasaException(
              f"Invalid value `{value}` for variable `{variable_name}`. "
              f"Available values are `{true_values + false_values}`"
          )
      return value.lower() in true_values
  
imports: import copy
  import inspect
  import logging
  import logging.config
  import logging.handlers
  import os
  import shutil
  import tempfile
  import warnings
  from pathlib import Path
  from types import TracebackType
  from typing import Any, Coroutine, Dict, List, Optional, Text, Type, TypeVar, Union, ContextManager, Set, Tuple
  from socket import SOCK_DGRAM, SOCK_STREAM
  import numpy
  import rasa.utils.io
  from rasa.constants import DEFAULT_LOG_LEVEL_LIBRARIES, ENV_LOG_LEVEL_LIBRARIES, ENV_LOG_LEVEL_MATPLOTLIB, ENV_LOG_LEVEL_RABBITMQ, ENV_LOG_LEVEL_KAFKA
  from rasa.shared.constants import DEFAULT_LOG_LEVEL, ENV_LOG_LEVEL, TCP_PROTOCOL
  from rasa.shared.exceptions import RasaException
  import rasa.shared.utils.io
label_desc: Use image node_id 25 for calling a global function with example usage: get_bool_env_variable(variable_name, default_variable_value) and returns: unknown