def param_to_tuple(param):
    """
    Convert param dictionary to a list of keys and a list of values.

    Parameters
    ----------

    param : dictionary
        parameters

    Returns
    -------

    list
        the keys of param
    list
        the values of param

    """

    if param is not None:
        keys, values = list(param.keys()), list(param.values())
    else:
        keys, values = (), ()
    return keys, values