cases br <;> simp [bne, toSint] at * <;> sorry_arith
sz : ℕ
n' m' : FinInt sz
br : Bool
r : FinInt sz
h :
  toSint
      (match next br r with
      | next false r => next true (next false r)
      | next true r => next true (next true r)) =
    toSint (next true n') + toSint (next true m')
h' : addfull n' m' = next br r
⊢ toSint (next true n' + next true m') =
    match next true n' + next true m' with
    | next false a => toSint (next true n') + toSint (next true m') + 2 ^ (sz + 1)
    | next true a => toSint (next true n') + toSint (next true m')
no goals