rem: Node *unary(np) Node *np;
add: unary(Node *np)
context: Node *unary(np)	Node *np;{	switch (rtok) {	case STAR:		rtok = relex();		return (unary(op2(STAR, np, NIL)));	case PLUS:		rtok = relex();		return (unary(op2(PLUS, np, NIL)));	case QUEST:		rtok = relex();		return (unary(op2(QUEST, np, NIL)));	default:		return (np);	}}