if the following are true:

• expression state at time 36 = "iterate_args"
• arguments stack at time 36 = [ [ last_name, [ ] ], [ ] ]
• parent stack at time 36 = [ self."last_name" = last_name, [ ] ]

then parent stack at time 37 = [ self."last_name" = last_name, [ ] ]

Start from the conclusion and work back up the proof. Click the arrow to show the parents.