static int nlLogic_numberOfLinesReferenced(Exp e) {
  if (e cast And)
    ret max(nlLogic_numberOfLinesReferenced(e.a), nlLogic_numberOfLinesReferenced(e.b));
  if (e cast Func) {
    new Matches m;
    if (startsWith(e.name, "line", m))
      ret parseIntOpt(m.rest());
  }
  ret 0;
}