Search the list in hash bucket HashTable.aa

[AaronGoldman]

In java I would often program defensively

  search = { list key ->
    list ? (
      list.key && list.key.eq(key) ? list.val : search(list.next,  key)
    )
  };

but in AA we some types are not nullable so the check for list.key may be harmful as it fails to assert the non Null property of list.key

  search = { list key ->
    list ? (
      list.key.eq(key) ? list.val : search(list.next,  key)
    )
  };