data available?                                                                                                                                                                                                                                                                                                                   
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                    out                                                     
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                          read data                                                                                                                                                                                                                                                                                         
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                           warning                                                                                                          
                                                                                                                                                      dsc_4                                                                                                                                                                                                                                 
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                            
                                                              generate diagrams                                                                                                                                                                                                                                                                                                             
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                  inc                                                                                                                                                                                                                                       
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                            
                                         foo as starting label                                                                                                                                                                                                                                                                                                                              
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                         out
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                          read data                                                                                                                                                                                                                                                                                         
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                      This is backward                                                                      
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                            
                                                              generate diagrams                                                                                                                                                                                                                                                                                                             
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                      dsc_6                                                                                                                                                                                                                                 
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                                                                                                                                                                            
                                                                                          more data?                                                                                                                                                                                                                                                                                     inc