lane1                                                                                                                      lane2                       
                                                                                                                                                                                        
                                                                                                                                                                                        
                                                                                                                                                                                        
                                                                                                                                                                                        
                     no                                                                                                                                          yes                    
                                                        condition                                                                                                                       
                                                                                                                                                                                        
                                                                                                                                                                                        
                                                                                                                                                                                        
                                                                                                                                                                                        
                                                                                                                                                                            do something