(match
  leaf
  (match
    (w{mono} var)
    (match
      (w{mono} (let:tree:cf node var))
      (w{l2xy mono}
        (let:tree:cf
          (tick (shift app))
          (match:tuple
            (match
              (w leaf)
              (w{mono} (let:tree:cf node (let:tree:cf node (let:tree:cf node var))))
            )
          )
        )
      )
    )
  )
)
