simp [addWithCarry, toNat, toNatHelper, bound_zero]
val✝¹ val✝ x✝ : Fin 2
⊢ addWithCarry (bit val✝¹) (bit val✝) x✝ =
    ({ val := (toNat [] (bit val✝¹) + toNat [] (bit val✝) + ↑x✝) / bound [],
        isLt := (_ : (toNat [] (bit val✝¹) + toNat [] (bit val✝) + ↑x✝) / bound [] < 2) },
      ofNat [] (toNat [] (bit val✝¹) + toNat [] (bit val✝) + ↑x✝))
no goals