pushValue (\u1 -> (\u2 -> u1 Term))
<hidden>:
| lift2Value (\u1 -> (\u2 -> u1 u2))
| read ('b' ==)
| lift2Value (\u1 -> (\u2 -> u1 u2))
| ret
catchException "fail"
  <try>
  | pushValue (\u1 -> (\u2 -> (\u3 -> 'a' : u2 u3)))
  | read ('a' ==)
  | lift2Value (\u1 -> (\u2 -> u1 u2))
  | call <hidden>
  | lift2Value (\u1 -> (\u2 -> u1 u2))
  | popException "fail"
  | refJoin <hidden>
  <handler>
    pushInput
    lift2Value Term
    choicesBranch [(\u1 -> u1)]
      <branch>
      | pushValue (\u1 -> u1)
      | refJoin <hidden>
      <default>
        raiseException "fail"