foo as starting label                                                                                                                                                                                                                                                    
                                                                                                                                                                                                                                                                                              
                                                                                                                                                                                                                                                                                              
                                                                                                                                                                                                                                                                                              
                                                                                                                                                                                                                                                                                              
                                                                      read data                                                                                                                                                                                                               
                                                                                                                                                                                                                                                                                              
                                                                                                                                                                                                                                                                                              
                                                                                                                                                                                                                                                                              This is backward
                                                                                                                                                                                                                                                                                              
                                                                                                                                                                                                                                                                                              
                                                                                                                                                                                                                                                                                              
                                          generate diagrams                                                                                                                                                                                                                                   
                                                                                                                                                                                                                                                                                              
                                                                                                                                                                                                                                                                                              
                                                                                                                                                                                                                                                                                              
                                                                      more data?