anchor.diff:          static member Custom(key: string, value: obj): TransitionGroupProp =
               unbox(key, value)
   
  +    /// The transition element lets you describe a transition from one element
  +    /// state to another _over time_ with a simple declarative API. Most commonly
  +    /// It's used to animate the mounting and unmounting of Component, but can also
  +    /// be used to describe in-place transition states as well.
  +    ///
  +    /// By default the `transition` element does not alter the behavior of the
  +    /// element it renders, it only tracks Enter and Exit states for the elements.
  +    /// It's up to you to give meaning and effect to those states. For example we can
  +    /// add styles to a element when it enters or exits.
       let transition (props: TransitionProp list) (child: React.ReactElement): React.ReactElement =
           let props = (TransitionProp.Children !^child)::props
           ofImport "Transition" "react-transition-group" (keyValueList CaseRules.LowerFirst props) []
   
  +    /// The transition element lets you describe a transition from one component
  +    /// state to another _over time_ with a simple declarative API. Most commonly
  +    /// It's used to animate the mounting and unmounting of Component, but can also
  +    /// be used to describe in-place transition states as well.
  +    ///
  +    /// By default the `transition` element does not alter the behavior of the
  +    /// element it renders, it only tracks Enter and Exit states for the elements.
  +    /// It's up to you to give meaning and effect to those states. For example we can
  +    /// add styles to a element when it enters or exits.
       let transitionWithRender (props: TransitionProp list) (render: TransitionStatus -> React.ReactElement): React.ReactElement =
           let props = (TransitionProp.Children !^render)::props
           ofImport "Transition" "react-transition-group" (keyValueList CaseRules.LowerFirst props) []
   
  +    /// A transition element using CSS transitions and animations.
  +    /// See `transition` for more information.
       let cssTransition (props: CSSTransitionProp list) (child: React.ReactElement): React.ReactElement =
           let props = (CSSTransitionProp.Children !^child)::props
           ofImport "CSSTransition" "react-transition-group" (keyValueList CaseRules.LowerFirst props) []
   
  +    /// A transition element using CSS transitions and animations.
  +    /// See `transitionWithRender` for more information.
       let cssTransitionWithRender (props: CSSTransitionProp list) (render: TransitionStatus -> React.ReactElement): React.ReactElement =
           let props = (CSSTransitionProp.Children !^render)::props
           ofImport "CSSTransition" "react-transition-group" (keyValueList CaseRules.LowerFirst props) []
   
  +    /// The `transitionGroup` element manages a set of `transition` elements
  +    /// in a list. Like with the `transition` element, `transitionGroup`, is a
  +    /// state machine for managing the mounting and unmounting of elements over
  +    /// time.
       let transitionGroup (props: TransitionGroupProp list) (children: React.ReactElement list): React.ReactElement =
           ofImport "TransitionGroup" "react-transition-group" (keyValueList CaseRules.LowerFirst props) children
  
positive.code: 
      [<RequireQualifiedAccess>]
      type TransitionProp =
          | In of bool
          | Appear of bool
          | Enter of bool
          | Exit of bool
          | MountOnEnter of bool
          | UnmountOnExit of bool
          | Timeout of U2<int, Timeout>
          | AddEndListener of (Browser.HTMLElement -> (unit -> unit) -> unit)
          | OnEnter of (Browser.HTMLElement -> bool -> unit)
          | OnEntering of (Browser.HTMLElement -> bool -> unit)
          | OnEntered of (Browser.HTMLElement -> bool -> unit)
          | OnExit of (Browser.HTMLElement -> unit)
          | OnExiting of (Browser.HTMLElement -> unit)
          | OnExited of (Browser.HTMLElement -> unit)
          | Children of U2<React.ReactElement, (TransitionStatus -> React.ReactElement)>
          | [<CompiledName "className">] Class of string
          | Ref of (obj -> obj)
          | Key of string
  
negative.code: 
      [<RequireQualifiedAccess>]
      type TransitionGroupProp =
          /// `transitionGroup` renders a <div> by default.
          /// You can change this behavior by providing a component prop.
          /// If you use React v16+ and would like to avoid a wrapping <div> element you can pass in `Component null`.
          /// This is useful if the wrapping div borks your css styles.
          | Component of React.ReactType
          /// You may need to apply reactive updates to a child as it is exiting.
          /// This is generally done by using cloneElement however in the case of an
          /// exiting child the element has already been removed and not accessible to the consumer.
          | ChildFactory of (React.ReactElement -> React.ReactElement)
          | [<CompiledName "className">] Class of string
          | Ref of (obj -> obj)
  