anchor.diff:                      "insert"     => chained (nameArg * !?(String + selectionCallback Element)?before)
                       "remove"     => chained O
   
  -                    // TODO: datum, filter, sort, order, each - can make use of `t` parameter
                       "datum"      => chained (Obj + selectionCallback Obj)?value
                       "filter"     => chained (String + selectionCallback Bool)?selector
                       "sort"       => chained !?Comparator?comparator
  
positive.code:             selfG
              |+> Instance
                  [
                      // TODO: NameValuePair
                      "attr" => String ^-> Obj
                      "attr" => String * Obj ^-> self
                      "attr" => String * (WithThis Element t attrValue) ^-> self
  
negative.code:         ]
          |>! addToClassList
  
      let Iterable = !| Int + !| Float + !| String + !| Obj + Map + Set
      let Value = Int + Float + String + Obj
  
      let Nest =
          ChainedClassNew "Nest" <| fun chained ->
          [
  