code: def _load_from_file(metadata, load_func):
      
      config_filename = get_config_filename(metadata)
      if config_filename is None:
          return dict()
  
      with open(config_filename, "r") as file_:
          data = load_func(file_.read())
          return dict(data)
docs: Load configuration from a file.
  
      The file path is derived from an environment variable
      named after the service of the form FOO_SETTINGS.