anchor.diff:                  | "monoandroid50" -> Some (MonoAndroid MonoAndroidVersion.V5)
                   | "monoandroid60" -> Some (MonoAndroid MonoAndroidVersion.V6)
                   | "monoandroid70" | "monoandroid7.0"-> Some (MonoAndroid MonoAndroidVersion.V7)
  +                | "monoandroid71" | "monoandroid7.1"-> Some (MonoAndroid MonoAndroidVersion.V71)
                   | "monomac" | "monomac10" | "monomac1" -> Some MonoMac
                   | "xamarinios" | "xamarinios10" | "xamarinios1" | "xamarin.ios10" -> Some XamariniOS
                   | "xamarinmac" | "xamarinmac20" | "xamarin.mac20" -> Some XamarinMac
  
positive.code:         | MonoAndroidVersion.V5    -> "v5.0"
          | MonoAndroidVersion.V6    -> "v6.0"
          | MonoAndroidVersion.V7    -> "v7.0"
  
  [<RequireQualifiedAccess>]
  type WindowsVersion =
  
negative.code:     | V5
      | V6
      | V7
      | V71
      member this.ShortString() =
          match this with
          | MonoAndroidVersion.V1    -> ""
  