anchor.diff:      static member op_ErasedCast(x:'c) = Case3 x
   
   /// Erased union type to represent one of four possible values.
  -/// More info: http://fable.io/docs/interacting.html#Erase-attribute
  +/// More info: https://fable.io/docs/communicate/js-from-fable.html#erase-attribute
   type [<Erase>] U4<'a, 'b, 'c, 'd> =
       | Case1 of 'a
       | Case2 of 'b
  
positive.code:     abstract ResolveType: unit -> Type
  
  /// Erased union type to represent one of two possible values.
  /// More info: http://fable.io/docs/interacting.html#Erase-attribute
  type [<Erase>] U2<'a, 'b> =
      | Case1 of 'a
      | Case2 of 'b
  
negative.code:     inherit Attribute()
  
  /// Function calls will be replaced by inlined JS code.
  /// More info: https://fable.io/docs/communicate/js-from-fable.html#emit-when-f-is-not-enough
  type EmitAttribute(macro: string, isStatement: bool) =
      inherit Attribute()
      new (macro: string) = EmitAttribute(macro, isStatement=false)
  