call_callback_retnr(
    callback_T	*callback,
    int		argcount,	// number of "argvars"
    typval_T	*argvars)	// vars for arguments, must have "argcount"
				// PLUS ONE elements!
{
    typval_T	rettv;
    varnumber_T	retval;

    if (call_callback(callback, 0, &rettv, argcount, argvars) == FAIL)
	return -2;

    retval = tv_get_number_chk(&rettv, NULL);
    clear_tv(&rettv);
    return retval;
}
call_callback_retnr(
    callback_T	*callback,
    int		argcount,	 
    typval_T	*argvars)	 
				 
{
    typval_T	rettv;
    varnumber_T	retval;

    if (call_callback(callback, 0, &rettv, argcount, argvars) == FAIL)
	return -2;

    retval = tv_get_number_chk(&rettv, NULL);
    clear_tv(&rettv);
    return retval;
}