anchor.diff:                   Error.TypeMismatch
                      (Int "t", Type.Bool ())) ])
   
  +
   module ArithmeticExprs =
  +    open Starling.Core.Pretty
  +    open Starling.Lang.Modeller.Pretty
  +
       let check (env : VarMap) (ast : Expression) (expectedExpr : IntExpr<Sym<Var>>) =
  -        let actualIntExpr = okOption <| modelIntExpr env environ id ast
  -        AssertAreEqual(Some expectedExpr, actualIntExpr)
  +        assertOkAndEqual
  +            expectedExpr
  +            (modelIntExpr env environ id ast)
  +            (printExprError >> printUnstyled)
   
       [<Test>]
       let ``test modelling (1 * 3) % 2`` ()=
  
positive.code:     { ViewProtos = ticketLockProtos
        SharedVars = shared
        ThreadVars = environ }
  
  module ViewPass =
      let check (view : View) (expectedCView : CView) =
  
negative.code:                     (CFunc.Func (vfunc "holdLock" []))
                      None))
  
  
  module ViewFail =
      let check (view : View) (expectedFailures : ViewError list) =
          let actualErrors = failOption <| modelCView context view
  