endless loop
                                                                                                               
                                                                                                               
                                                                                                               
                                                                                                               
                                                                                   condition met?              
                                                                                                               
                                                                                                               
                                                                                                               
                                                                                                               
                                                                                             activity 1        
                                                                                                               
                                                                                                               
                                                                                                               
                                                                        while condition                        
                                                                                                               
                                                                                                               
                                                                                                               
                                                                                                               
                                                                                             activity 2