x : Nat | id (twice (id x)) x : Nat | id x x : Nat | x x : Nat | id (twice x) convInConv.lean:14:8-14:12: warning: declaration uses 'sorry' y : Nat | (fun x => x + y = 0) = fun x => False y : Nat | fun x => x + y = 0 case h y x : Nat | y + x = 0 y : Nat | (fun x => y + x = 0) = fun x => False y : Nat ⊢ (fun x => y + x = 0) = fun x => False