In imperative programming, your code can execute in two states, valid and not-valid. You start in valid state, then any validation failure returns you to non-va

In imperative programming, your code can execute in two states, valid and not-valid. You start in valid state, then any validation failure returns you to non-valid state and you remain there. Pretty much the core of any validation technique without bells and whistles. valid = true if valid and not check1(): valid = false if valid and not check2(): valid = false ...