anchor.diff:          MainCommand.AddNuGet, "add nuget <nuget-uri> : add nuget uri"
           MainCommand.ListNuget, "list nuget : list NuGet feeds"
           MainCommand.Unknown, ""
  -        MainCommand.DropView, "pending view <viewId> : create view with modified and depending repos"
           MainCommand.DropView, "drop view <viewId> : drop view"
           MainCommand.ListView, "list view : list views"
           MainCommand.DescribeView, "describe view <name> : describe view"
  
positive.code: 
      | "add" -> Some Add
      | "drop" -> Some Drop
      | "pending" -> Some Pending
      | "list" -> Some List
      | "describe" -> Some Describe
  
  
negative.code: 
      | Add
      | Drop
      | List
      | Describe
  
  