def get_extra(cls, name=None):
    """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.
    """
    if not name:
      return cls._extra_config
    return cls._extra_config.get(name, None)