Theorem: MyGroup.mul_right_inv (LeanCourse/MIL/C02_Basics/S02_Proving_Identities_in_Algebraic_Structures.lean)

State before:
G : Type u_1
inst✝ : Group G
a : G
⊢ a * a⁻¹ = 1
Tactic:
sorry
State after:
no goals