anchor.diff:              | true -> ConfigAuthentication(username, password)
               | false -> PlainTextAuthentication(username, password)
           | _ -> failwith "invalid auth"
  +
   /// Represents type of NuGet packages.config file
   type NugetPackagesConfigType = ProjectLevel | SolutionLevel
   
  
positive.code:     static member Parse(s : string) = 
          match s with 
          | "encrypt" -> ok Encrypt
          | "plaintext" -> ok  Plaintext
          | "selective" -> ok Selective
          | _ ->  InvalidCredentialsMigrationMode s |> fail
  
  
negative.code:             |> fail
  
      static member OverrideConfig nugetConfig (configNode : XmlNode) =
          let getAuth key = 
              let getAuth' authNode =
                  let userName = authNode |> tryGetValue "Username"
  