anchor.diff:  type QuotationEvaluator() = 
   
       static member ToLinqExpression (e: Microsoft.FSharp.Quotations.Expr) = e.ToLinqExpression()
  -
      
       static member CompileUntyped (e : Microsoft.FSharp.Quotations.Expr) = e.CompileUntyped()
   
  
positive.code:             | ConvUInt16Q (_, [ty],[x1]) -> Expression.Convert(ConvExpr env x1, typeof<uint16>) |> asExpr
              | ConvUInt32Q (_, [ty],[x1]) -> Expression.Convert(ConvExpr env x1, typeof<uint32>) |> asExpr
              | ConvUInt64Q (_, [ty],[x1]) -> Expression.Convert(ConvExpr env x1, typeof<uint64>) |> asExpr
              | ConvDoubleQ (_, [ty],[x1]) -> Expression.Convert(ConvExpr env x1, typeof<double>) |> asExpr
               /// REVIEW: convert with method witness
  
              | CheckedConvCharQ (_, [ty],[x1])  -> Expression.ConvertChecked(ConvExpr env x1, typeof<char>) |> asExpr
  
negative.code:         // Generic cases 
          | Patterns.Var(v) -> 
                  try
                      Map.find v env.varEnv
                  with
                  |   :? KeyNotFoundException when v.Name = "this" ->
  