anchor.diff:      member __.ExistsByExpressionAsync (expr): Task<bool> = 
           failwith "Not implemented"
   
  -    member __.ExistsByObjectAsync (obj): Task<bool> = 
  -        failwith "Not implemented"
  -
       member __.ExistsBySelectorAsync (dict): Task<bool> = 
  -        failwith "Not implemented"
  +        dict 
  +        |> dictToMap findExpressionToFs
  +        |> existsBySelector
  +        <| client
  +        |> task
   
       member __.ListWithDocsAsync (?options): Task<ListResponse<'doctype>> =
           failwith "Not implemented"
  
positive.code:         member val Skip = System.Nullable<int>() with get, set
          member val Group = System.Nullable<bool>() with get, set
          member val GroupLevel = System.Nullable<int>() with get, set
  
      type Configuration(couchUrl: string, databaseName: string) = 
          member val CouchUrl = couchUrl with get, set
  
negative.code:     member __.CountByExpressionAsync (exp): Task<int> = 
          failwith "Not implemented"
  
      member __.CountBySelectorAsync (dict): Task<int> = 
          dict
          |> dictToMap findExpressionToFs 
          |> countBySelector 
          <| client
          |> task
  
      member __.ExistsAsync (id, ?rev: string): Task<bool> = 
          client 
  