anchor.diff:  type DotNetCoreVersion = 
       | V1_0
       | V1_1
  +    | V2_0
       override this.ToString() =
           match this with
           | V1_0 -> "v1.0"
           | V1_1 -> "v1.1"
  -
  +        | V2_0 -> "v2.0"
       member this.ShortString() =
           match this with
           | DotNetCoreVersion.V1_0 -> "10"
           | DotNetCoreVersion.V1_1 -> "11"
  +        | DotNetCoreVersion.V2_0 -> "20"
   
   module KnownAliases =
       let Data =
  
positive.code:                 | "netstandard14" -> Some(DotNetStandard DotNetStandardVersion.V1_4)
                  | "netstandard15" -> Some(DotNetStandard DotNetStandardVersion.V1_5)
                  | "netstandard16" -> Some(DotNetStandard DotNetStandardVersion.V1_6)
                  | "netcore10" -> Some (DotNetCore DotNetCoreVersion.V1_0)
                  | "netcore11" -> Some (DotNetCore DotNetCoreVersion.V1_1)
                  | v when v.StartsWith "netstandard" -> Some(DotNetStandard DotNetStandardVersion.V1_6)
                  | _ -> None
              result)
  
negative.code:     | V1_4
      | V1_5
      | V1_6
      | V2_0
      override this.ToString() =
          match this with
          | V1_0 -> "v1.0"
  