rem: follow(v) Node *v;
add: follow(Node *v)
context: follow(v)	Node *v;		/* collects leaves that can follow v into setvec */{	Node *p;	if (type(v) == FINAL)		return;	p = parent(v);	switch (type(p)) {	case STAR:	case PLUS:		first(v);		follow(p);		return;	case OR:	case QUEST:		follow(p);		return;	case CAT:		if (v == left(p)) {	/* v is left child of p */			if (first(right(p)) == 0) {				follow(p);				return;			}		}		else		/* v is right child */			follow(p);		return;	default:		ERROR "unknown type %d in follow", type(p) FATAL;		break;	}}