This surprised me a bit when I tried to create a nested loop through a coll with non-successive indices.
- Create a named coll, give it some indexed data (1, one; 2, two; 3, three;)
- Make a copy of it.
- pass to the first coll the message [start, next]. It will send out the contents of its first index ("one").
- pass it another message, [next]. It will send out the contents of the second index ("two").
- pass to the SECOND coll a [start] message.
- pass to the FIRST coll a [next] message. It will send out the contents of the first index ("one"), rather than the third ("three").