+ * built once with the combination of the date and item ID.
+ * e.g. smallHash('20111006_131924' . 142) --> eaWxtQ
+ *
+ * @warning before v0.8.1, smallhashes were built only with the date,
+ * and their value has been preserved.
+ *
+ * @param string $text Create a hash from this text.
+ *
+ * @return string generated small hash.