def _get_system_ps(b, item, context='component'):
    """
    parses the input arg (either twig or PS) to retrieve the actual parametersets
    """
    # TODO: make this a decorator?
    if isinstance(item, list) and len(item)==1:
        item = item[0]

    if isinstance(item, ParameterSet):
        return item.filter(context=context, check_visible=False)
    elif isinstance(item, str):
        return b.filter(item, context=context, check_visible=False)
    else:
        logger.debug("_get_system_ps got {}".format(item))
        raise NotImplementedError("_get_system_ps does not support item with type: {}".format(type(item)))
parses the input arg (either twig or PS) to retrieve the actual parametersets