anchor.diff:              render = fun r -> r var
           }
   
  -    let Yield value =
  -        YieldVar (Var.Create value)
  +    let Yield init =
  +        YieldVar (Var.Create init)
   
       let YieldFailure () =
           let var = Var.Create JS.Undefined<_> :> Var<_>
  
positive.code:         member this.ReturnFrom (p: Form<_, _ -> _>) = p
  
          [<Inline>]
          member this.Yield x = Yield x
  
          [<Inline>]
          member this.YieldFrom (p: Form<_, _ -> _>) = p
  
negative.code:             | Success (Failure mx) -> Failure mx
              | Success (Success x) -> Success (f x)
  
      static member Bind (f: 'T -> Result<'U>) (r: Result<'T>) : Result<'U> =
          match r with
          | Failure m -> Failure m
          | Success x -> f x
  
  