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 ***
