if the following are true:

• Expression Stack at time t = [ [ ], [ [ obj.attribute = val, ys ], rest ] ]
• Value Stack at time t = [ [ value, [ Python reference idx, [ ] ] ], [ next_level, other_levels ] ]
• the element at index idx of stack (Python Object Store at time t) = Python object: entries

then Value Stack at time (t + 1) = [ [ None, next_level ], other_levels ]