anchor.diff:  
   type ITypeHandler =
       abstract member GetKnownTypes : CoreVariableType seq
  -    abstract member GetMapping : targetType : System.Type -> TypeMapping option
  +    abstract member GetMapping : targetType : Type -> TypeMapping option
   
   type ZeroTypeHandler() =
       interface ITypeHandler with
  
positive.code:             else None
  
  type RootTypeHandler(customContext : ITypeHandler -> ITypeHandler) as this =
      let mutable context : ITypeHandler = Unchecked.defaultof<ITypeHandler>
      do
          context <-
  
negative.code: type EnumerableTypeContext(rootHandler : ITypeHandler) =
      let translateEnumerable
          (cons : ConstructorInfo) // constructor taking IEnumerable<clrElementType>
          (clrElementType : Type)
          value =
          let collectionType = typedefof<List<_>>.MakeGenericType([|clrElementType|])
          let collectionAdd = collectionType.GetMethod("Add", [|clrElementType|])
  