code: def get_extra(cls, name=None):
      
      if not name:
        return cls._extra_config
      return cls._extra_config.get(name, None)
docs: Gets extra configuration parameters.
  
      These parameters should be loaded through load_extra or load_extra_data.
  
      Args:
        name: str, the name of the configuration data to load.
  
      Returns:
        A dictionary containing the requested configuration data. None if
        data was never loaded under that name.