anchor.diff:    endcase;
   
   // Turn an item into a singleton statement if it is an EnsureItem.
  -function List#(Bool) getEnsureItem(Item item) =
  +function List#(Tuple2#(Bool, Reg#(Bool))) getEnsureItem(Item item) =
     case (item) matches
       tagged EnsureItem .a: return Cons(a, Nil);
       default: return Nil;
  
positive.code:   ID_Params idParams =
      ID_Params {
        rst           : rst
      , initialDepth  : 10
      , testsPerDepth : 3000
      , incDepth      : incDepth
      };
  
    BlueCheck_Params params =
      BlueCheck_Params {
        showNonFire           : False
      , showNoOp              : False
      , useIterativeDeepening : True
      , useShrinking          : True
      , id                    : idParams
      , numIterations         : 5
      };
  
    return params;
  
negative.code:   let stmtMsgs       = map(tpl_2, stmtItems);
    let actions        = map(tpl_3, actionItems);
    let stmts          = map(tpl_3, stmtItems);
    let ensureBools    = map(tpl_1, ensureItems);
    let ensureShows    = map(tpl_2, ensureItems);
  
    // Setup state machine for equivalence checking.
    // Note state 0 is a no-op state.
  