code: func (h Host) Diff(altHost Host) (added []Port, removed []Port) {
  	targetPorts := h.Ports
  	altPorts := altHost.Ports
  
  	addedWithClosed := array.Except(altPorts, targetPorts).([]Port)
  	for _, add := range addedWithClosed {
  		if add.State != "closed" {
  			added = append(added, add)
  		}
  	}
  	removedWithClosed := array.Except(targetPorts, altPorts).([]Port)
  	for _, remove := range removedWithClosed {
  		if remove.State != "closed" {
  			removed = append(removed, remove)
  		}
  	}
  
  	return
  }
docs: // Diff gets the difference between the the target host and the argument host.
  //The first returned value is the added ports and the second returned value is
  // the removed ports.