Mutability

[paulyoung]

The data parameter of promises is the only mutable object in decision trees.

How are other objects made immutable? e.g. choice

[paulyoung]

Items are immutable, meaning they will always remain in the Choice.attributes.items object

[cbchouinard]

I'll clarify that point in the doc, in fact even items are not immutable, its the collection of items that is. eating an items add the item to the eatenItems collection and when you get an item, the list of available items is filtered out from the eatenItems collection.