docs: def _get_config_dict_from_file(config_path=None):
      """Return value if key exists in file.
  
      Return empty string ("") if key or file does not exist.
      """
      if config_path is None:
          config_path = DEFAULT_CONFIG_PATH
  
      # Default (empty) content will be used if config file does not exist.
      config_content = {}
  
      # If the config file exists we use that content.
      if os.path.isfile(config_path):
          with open(config_path) as fh:
              config_content = json.load(fh)
  
      return config_content