call_func_retstr(
    char_u      *func,
    int		argc,
    typval_T	*argv)
{
    typval_T	rettv;
    char_u	*retval;

    if (call_vim_function(func, argc, argv, &rettv) == FAIL)
	return NULL;

    retval = vim_strsave(tv_get_string(&rettv));
    clear_tv(&rettv);
    return retval;
}
call_func_retstr(
    char_u      *func,
    int		argc,
    typval_T	*argv)
{
    typval_T	rettv;
    char_u	*retval;

    if (call_vim_function(func, argc, argv, &rettv) == FAIL)
	return NULL;

    retval = vim_strsave(tv_get_string(&rettv));
    clear_tv(&rettv);
    return retval;
}