anchor.diff:                  |> Async.AwaitTaskCorrect
                   |> Async.Ignore
   
  -        with :? QueueDoesNotExistException -> ()
  +        with QueueNotFoundException -> ()
       }
   
       member client.QueueNameExists (queueName : string) = async {
  
positive.code: 
      // SQS limits you to up to 20 seconds of long polling wait time
      let maxWaitTime = TimeSpan.FromSeconds 20.
  
  [<Sealed; AutoSerializable(false)>]
  type SqsDequeueMessage internal (account : IAmazonSQS, queueUri : string, message : Message) =
  
negative.code: 
          match res with
          | Choice1Of2 res -> return Some res.QueueUrl
          | Choice2Of2 QueueNotFoundException -> return None
          | Choice2Of2 exn -> return! Async.Raise exn
      }
  
  