Actor 1                                                                                                                                                                Actor 2                                                                                                               
                                                                                                                                                                                                                                                                                                         
                                        send something                                                                                                                                                                                                                                                   
                                                                                                                                                                                                                                                                                                         
                                                                                                                                                                                                                                                                                                         
                                                                                                                                                                                                                                                                                                         
                                                                                                             is ok                                                                                                                                                                                       
                                                                                                                                                                                              check that something ?                                                                                     
                                                                                                                                                                                                                                                                                                         
                                                                                                                                                                                                                                                                                                   not ok
                                                                                                                                                                                                                                                                                                         
                                                                                                                                                                                                                                                                                                         
                                                                                                                                                                                                                                                                                                         
                                         do it better                                                                                                                                                                                                                                                    
                                                                                                                                                                                                                                                                                                         
                                                                                                                                                                                                                                                                                                         
                                                                                                                                                                                                                                                                                                         
                                                                                                                                                                                                                                                                                                         
                                                                                                                                                                                                                                                                                                         
                                                                                                                                                                                                                                                                                                         
                                                                                                                                                                                                                                                                    happy