Resp fn and then

addresses issue #239. when introducing unfiltered to java developers and you show them `~>` it's sometimes a turn off on the first date. this change provides a named alternative `andThen` which seems to make sense for what `~>` does. I'm open to other suggestions but I think we should have an alternative regardless. We could shorten it to just `and` or `then`. Thoughts? cc @n8han @chrislewis