def prep_sub_id(sub_id_input):
    """Processes subscription ID

    Args:
        sub_id_input: raw subscription id
    Returns:
        Processed subscription id

    """

    if not isinstance(sub_id_input, str):
        return ""

    if len(sub_id_input) == 0:
        return ""

    return "{" + sub_id_input.strip().upper() + "}"