anchor.diff:      [<CompiledName("PrintFormatToStringThenFail")>]
       let inline failwithf (fmt : Printf.StringFormat<'T, Choice<'U, exn>>) =
           Printf.ksprintf failwith fmt
  +
  +    //
  +    [<CompiledName("OfOption")>]
  +    let ofOption (value : 'T option) : Choice<'T, unit> =
  +        match value with
  +        | Some result ->
  +            Choice1Of2 result
  +        | None ->
  +            Choice2Of2 ()
  +
  +    //
  +    [<CompiledName("ToOption")>]
  +    let toOption (value : Choice<'T, 'Error>) : 'T option =
  +        match value with
  +        | Choice1Of2 result ->
  +            Some result
  +        | Choice2Of2 _ ->
  +            None
   
       /// <summary>
       /// When the choice value is <c>Choice1Of2(x)</c>, returns <c>Choice1Of2 (f x)</c>.
  
positive.code:     /// Creates a Choice representing an error value.
      /// The error value in the Choice is a new exception created with the specified message.
      [<CompiledName("FailWith")>]
      let inline failwith msg =
          Choice2Of2 <| exn msg
  
      /// Creates a Choice representing an error value.
  
negative.code:         | Some x -> Nullable<_> x
          | None -> Nullable<_> ()
  
      //
      [<CompiledName("OfChoice")>]
      let ofChoice (value : Choice<'T, 'Error>) : 'T option =
          match value with
          | Choice1Of2 result ->
              Some result
          | Choice2Of2 _ ->
              None
  
      //
      [<CompiledName("ToChoice")>]
      let toChoice (value : 'T option) : Choice<'T, unit> =
          match value with
          | Some result ->
              Choice1Of2 result
          | None ->
              Choice2Of2 ()
  
      //
      [<CompiledName("ToChoiceWith")>]
      let toChoiceWith (errorValue : 'Error) (value : 'T option) : Choice<'T, 'Error> =
          match value with
          | Some result ->
              Choice1Of2 result
          | None ->
              Choice2Of2 errorValue
  
      /// Creates an F# option from a value 'x'.
      /// When the specified condition is true, returns Some x; otherwise, None.
      [<CompiledName("Conditional")>]
  