program  TestValue (output);
	var  x, y : integer;

	procedure  NoEffect ( x, y : integer );
	begin
	    x := y;  y := 0;
	    writeln( x, y )
	end;

	begin
	    x := 1;  y := 2;
	    writeln( x, y );
	    NoEffect( x, y );
	    writeln( x, y )
	end.


	Self test on procedures which accept arguments, output of Testvalue is
	1  2
	2  0
	1  2