anchor.diff:                  let! results = parseAndCheckFile
                   return bindParsedInput results
           }
  -
   
       member checker.ParseAndCheckDocument(document: Document, options: FSharpProjectOptions, allowStaleResults: bool, userOpName: string, ?sourceText: SourceText) =
           async {
  
positive.code:                         return None // worker is cancelled at this point, we cannot return it and wait its completion anymore
                  }
  
          let bindParsedInput(results: (FSharpParseFileResults * FSharpCheckFileResults) option) =
              match results with
              | Some(parseResults, checkResults) ->
                  match parseResults.ParseTree with
                  | Some parsedInput -> Some (parseResults, parsedInput, checkResults)
                  | None -> None
              | None -> None
  
          if allowStaleResults then
              async {
                  let! freshResults = tryGetFreshResultsWithTimeout()
                      
                  let! results =
  
negative.code:         checker.ParseDocument(document, parsingOptions, sourceText=sourceText.ToString(), userOpName=userOpName)
  
      member checker.ParseAndCheckDocument(filePath: string, textVersionHash: int, sourceText: string, options: FSharpProjectOptions, allowStaleResults: bool, userOpName: string) =
          async {
              let parseAndCheckFile =
                  async {
                      let! parseResults, checkFileAnswer = checker.ParseAndCheckFileInProject(filePath, textVersionHash, sourceText, options, userOpName=userOpName)
                      return
                          match checkFileAnswer with
                          | FSharpCheckFileAnswer.Aborted -> 
                              None
                          | FSharpCheckFileAnswer.Succeeded(checkFileResults) ->
                              Some (parseResults, checkFileResults)
                  }
  
              let tryGetFreshResultsWithTimeout() =
                  async {
  