def list_as_tuple_hook(x):
    """Transform all list entries in a dictionary into tuples.

    This function can be used to load JSON files with tuples instead of lists.

    :param dict x: A dictionary.
    
    :return: The input dictionary, with lists transformed into tuples.

    """
    return {key: tuple(value)
            if isinstance(value, list)
            else value
            for key, value in x.items()}