[galaxy-dev] Dataset_Collections : an example of code for a tool ?

Hi, Your latest update is very exciting with the introduction of Dataset_Collections!!! It's very useful for us . I've been testing it in a new install of Galaxy and I can create a Dataset_Collection in my history. But with the reading of trello cards and this presentation : https://docs.google.com/presentation/d/1D4pbULfe3IbSRVF3xsWvp9GyAct4SNfHhufI... I've not yet found how to code a tool to use this collection and/or unique dataset. Is it possible to have the bowtie2 version (and or Merge Bam) with these 2 possibilities to have an example? And how can I see the icons in the formular which allow to switch between the use of unique dataset and the use of dataset collection, like is presented in the presentation ? Thanks. Julie