code: def _get_explicit_environ_credentials():
      
      explicit_file = os.environ.get(environment_vars.CREDENTIALS)
  
      if explicit_file is not None:
          credentials, project_id = _load_credentials_from_file(
              os.environ[environment_vars.CREDENTIALS])
  
          return credentials, project_id
  
      else:
          return None, None
docs: Gets credentials from the GOOGLE_APPLICATION_CREDENTIALS environment
      variable.