code: public static <T> DomContent each(Collection<T> collection, Function<? super T, DomContent> mapper) {
          return tag(null).with(collection.stream().map(mapper));
      }
docs: Creates a DomContent object containing HTML using a mapping function on a collection
  Intended usage: {@literal each(numbers, n -> li(n.toString()))}
  
  @param <T>        The derived generic parameter type
  @param collection the collection to iterate over, ex: a list of values "1, 2, 3"
  @param mapper     the mapping function, ex: {@literal "n -> li(n.toString())"}
  @return DomContent containing mapped data {@literal (ex. docs: [li(1), li(2), li(3)])}