// returns number of steps
static long stepAll(Steppable s) {
  long steps = 0;
  if (s != null) {
    var pingSource = pingSource();
    while true {
      ping(pingSource);
      if (s.step())
        ++steps;
      else
        break;
    }
  }
  ret steps;
}

Began life as a copy of #1018351