def METHOD_NAME(self, key: str, value: List[Any], unique: bool = False) -> dict:
    """Extend a list in config at key path.
    Args:
        key: Key to path to extend.
        value: List of values to extend by.
        unique: Only extend values if not already in values.
    Returns:
        Updated Config
    """
    to_update = list(deepcopy(self.get(key, value)))
    if unique:
        value = [v for v in value if v not in to_update]
    dpath.merge(to_update, value, flags=dpath.MERGE_ADDITIVE)
    self.set(key, to_update)
    return self.sync()