• the line at time t = i
• the tab at time t = j
• statement at line i, tab j = assign statement with target x and expression (Python constructor with name: class_name and arguments: args)
• Expression Stack at time t = [ [ ], [ ] ]
• Value Stack at time t = [ [ value, [ ] ], [ ] ]

then the line at time (t + 1) = i + 1