Like _index_list_of_values, but uses get to access and
    returns an empty list if the key is absent.
    Returns d[k] or [d[k]] if the value is not a list

def _get_index_list_of_values(d, k, def_value=None):
    """Like _index_list_of_values, but uses get to access and
    returns an empty list if the key is absent.
    Returns d[k] or [d[k]] if the value is not a list"""
    v = d.get(k, def_value)
    if v is None:
        return []
    if isinstance(v, list):
        return v
    return [v]