definition foo : ∀ {A : Type} [_inst_1 : group A] (a b : A), a * b = b * a :=
λ A _inst_1 a b, sorry
definition bla : ∀ {B : Type} [_inst_2 : group B] (b : B), b * 1 = b :=
λ B _inst_2 b, sorry
definition foo2 : ∀ {A : Type} [_inst_1 : group A] (a b : A), a * b = b * a :=
λ A _inst_1 a b, sorry
definition bla2 : ∀ {B : Type} [_inst_2 : group B] (b : B), b * 1 = b :=
λ B _inst_2 b, sorry