proposition: Lemma Id_sym_invol {A} (x y : A) (e : x = y) : id_sym (id_sym e) = e.
proof: Proof. destruct e. reflexivity. Defined.
imports: Coq.Program.Tactics Equations.Init Equations.Signature Equations.CoreTactics Equations.Type.Logic Equations.Type.Classes Equations.Type.EqDec