anchor.diff:  
     // Display message when a chosen state is a no-op
     Bool showNoOp;
  +
  +  // Statements to be added before and after a test run
  +  Stmt preStmt;
  +  Stmt postStmt;
   
     // Generate a checker based on an iterative deepening strategy
     // (If 'Invalid', a single random state walk is performed)
  
positive.code:     seq
        randomState.cntrl.init;
        testDone <= False;
        $display("=== Depth %0d, Test %0d ===", currentDepth, testNum);
        while (! testDone)
          action
  
negative.code:               seq
                  testDone <= False;
                  $display("=== Depth %0d, Test %0d ===", currentDepth, testNum);
                  params.preStmt;
                  while (! testDone)
                    action
                      await(!waitWire);
  