  To reversify an arbitrary sequential algorithm $A$, we gently instrument $A$
with bookkeeping machinery. The result is a step-for-step reversible algorithm
that mimics $A$ step-for-step and stops exactly when $A$ does.
  Without loss of generality, we presume that algorithm $A$ is presented as an
abstract state machine that is behaviorally identical to $A$. The existence of
such representation has been proven theoretically, and the practicality of such
representation has been amply demonstrated.
