CallSub.BAS -- Test BASIC Call and Sub Statements                               
The next printed line should be from the Subroutine.                            
                                                                                
This is written from the Subroutine.                                            
The value of variable <xarg>  is 5                                              
The value of variable <yarg$> is Hello                                          
The value of variable <tvar>  is 17                                             
The value of variable <tvar> is reset to  99                                    
Exiting Subroutine                                                              
                                                                                
This is back at the main program.                                               
The value of variable <testvar> is now  0                                       
Did it work?                                                                    
*** ALL TESTS PASSED ***                                                        
