anchor.diff:        Sources: string list
         /// Packages to update. Update all if empty.
         Ids: string list
  +      /// Version to update to. Default `None`. Used to upgrade/downgrade to a explicit version of a package.
  +      Version: string option
         /// Folder to store packages in. Default `./packages`.
         RepositoryPath: string
         /// Looks for updates with the highest version available within the same major and minor version as the installed package. Default `false`.
  
positive.code:     [   param.Sources |> argList "source"
          param.Ids |> argList "id"
          [param.RepositoryPath] |> argList "repositoryPath"
          (if param.Safe then "-safe" else "")
          (if param.Prerelease then "-prerelease" else "")
          (if param.NonInteractive then "-nonInteractive" else "")
  
negative.code:       Retries = 5
        Sources = []
        Ids = []
        Version = None
        RepositoryPath = "./packages"
        Safe = false
        Verbose = false
  