anchor.diff:             override __.Shrinker b = b |> a.Shrinker |> Seq.filter pred
          }
     
  -    ///A collection of default generators.
  +    ///A collection of default Arbitrary instances for some types.
       type Default with
           ///Generates (), of the unit type.
           static member Unit() = 
  
positive.code:             fromGenShrink(gen, shrink)
              |> convert DoNotSize DoNotSize.Unwrap
  
          ///Generate arbitrary int32 that is unrestricted by size.
          static member DoNotSizeInt32() =
              //let gen = Gen.choose(Int32.MinValue, Int32.MaxValue) doesn't work with random.fs, 
              //so using this trick instead
  
negative.code:             fromGenShrink ( Gen.sized (fun n -> Gen.choose (-n,n)),
                              shrinkNumber)
  
          ///Generate arbitrary int32 that is uniformly distributed in the whole range of int32 values.
          [<Obsolete("Renamed to DoNotSizeInt32.")>]
          static member DontSizeInt32() =
              //let gen = Gen.choose(Int32.MinValue, Int32.MaxValue) doesn't work with random.fs, 
  