$use Compare StdIO ;

Main = { <"=" ('a') ('a') >;
         <PrintLN 'fail'>;
       },
       { <"=" ('a') ('b')>;
         <PrintLN 'fail: content of expressions are not equal'>;
       },
       { <"=" ('a') (('a'))>;
         <PrintLN 'fail expressions are not equal'>;
       };