1. State = Initial State + UserCreated(name: John) applied
new User() and u.name = John
State: user {name = John}
2. State = Previous (after 1) State + UserActivated applied
u {name = John} and u.active = true
State: user {name = John, active = true}
3. State = Previous (after 2) State + UserNameChanged applied
user { name = John, active = true} and u.name = Barry
State: user {name = Barry, active = true}
...