code: def test_load_dash_env_vars_refects_to_os_environ(empty_environ):
      for var in DASH_ENV_VARS.keys():
          os.environ[var] = "true"
          vars = load_dash_env_vars()
          assert vars[var] == "true"
  
          os.environ[var] = "false"
          vars = load_dash_env_vars()
          assert vars[var] == "false"
  
imports: import os
  import logging
  import pytest
  from flask import Flask
  from dash import Dash, exceptions
  from dash._configs import pathname_configs, DASH_ENV_VARS, get_combined_config, load_dash_env_vars
  from dash._utils import AttributeDict
  from dash._get_paths import app_get_asset_url, app_get_relative_path, app_strip_relative_path, get_asset_url, get_relative_path, strip_relative_path
label_desc: Use image node_id 13 for calling a global function with example usage: test_load_dash_env_vars_refects_to_os_environ(empty_environ) without return types