anchor.diff:                 yield ReadOnly opts.IsReadOnly :> IHTMLProp
                  yield Props.Type opts.Type :> IHTMLProp
                  if Option.isSome opts.Id then yield Props.Id opts.Id.Value :> IHTMLProp
  +               if Option.isSome opts.Key then yield Props.Key opts.Key.Value :> IHTMLProp
                  if Option.isSome opts.Value then yield Props.Value opts.Value.Value :> IHTMLProp
                  if Option.isSome opts.DefaultValue then
                      yield Props.DefaultValue opts.DefaultValue.Value :> IHTMLProp
  
positive.code:         | IsRounded
          /// Set `Value` HTMLAttr
          | Value of string
          /// Set `DefaultValue` HTMLAttr
          | DefaultValue of string        
          /// `Ref` callback that sets the value of an input textbox after DOM element is created.
  
negative.code:             | Type type' -> { result with Type = ofType type' }
              | Color color -> { result with Color = ofColor color |> Some }
              | Id id -> { result with Id = Some id }
              | Key k -> { result with Key = Some k }
              | Disabled disabled -> { result with Disabled = disabled }
              | IsReadOnly state -> { result with IsReadOnly = state }
              | IsStatic state -> { result with IsStatic = state }
  