ptree_name
ptree_name(O_ERR|O_NONL, np->u.event.ename);
ptree_name(O_WARN|O_NONL, lhs);
ptree_name(olevel|O_NONL, rhs->u.stmt.np);
ptree_name(O_ERR|O_NONL, rhs);
void ptree_name(int flags, struct node *np);