layer ext1;

import firstPackage.*;

refines State_machine root {

   // from ext 1
   States d;
   States e;

   // from ext1
   Transition e2 : d -> e 
   condition m!=null
   do { /* action 2 */ }

   Transition e3 : c -> d
   condition true
   do { /* action 3 */ }

   Exit b { /* action a */ }
}
