private void finishNode(InstructionImpl instruction) {
   final InstructionImpl popped = myProcessingStack.pop();
   if (!instruction.equals(popped)) {
     String description =
         "popped: "
             + popped.toString()
             + " : "
             + popped.hashCode()
             + "   ,  expected: "
             + instruction.toString()
             + " : "
             + instruction.hashCode();
     error(description);
   }
 }