BTW dealing with this issues made me discover that "expression" input port is of type "List of math symbols". Seems that it works fine when connected to a "share value" node, but there's no way to connect to other kind o f ports, or set other generic type ports to that specific type. I'd like to know if there's a way to convert from text type to that type so that math expression could be somehow calculated on runtime. Don't know if this is a FR or there's something I'm missing.
Rethinking to this, I propouse a different behaviour. a thing like this:
if a new list reaches the node if count item of the new list < actual internal node position actual internal node position = count item of the new list
This way, the last backward event I described in point 3 would output item 2 of the new list. This behaviour seems to me more reasonable.