static <D, T> DataSourceHandler<D, T> of(
        final Function<D, T> extractor,
        final BiFunction<? super T, Isolation, Isolation> isolationConfigurator,
        final Consumer<? super T> beginner,
        final Consumer<? super T> committer,
        final Consumer<? super T> rollbacker,
        final Consumer<? super T> closer
    ) {
        return new DataSourceHandlerImpl<>(extractor, isolationConfigurator, beginner, committer, rollbacker, closer);
    }
Returns a BiFunction that, when applied, sets a new Isolation level and
then returns the previous Isolation level.

@return a BiFunction that, when applied, sets a new Isolation level and
then returns the previous Isolation level
runtime-parent/runtime-core/src/main/java/com/speedment/runtime/core/component/transaction/DataSourceHandler.java