Theorem: Pos.mul_comm (Extra/Pos/Lemmas.lean)

State before:
x y : Pos
⊢ x * y = y * x
Tactic:
by_toNat
State after:
x y : Pos
⊢ x.toNat * y.toNat = y.toNat * x.toNat

State before:
x y : Pos
⊢ x.toNat * y.toNat = y.toNat * x.toNat
Tactic:
exact Nat.mul_comm ..
State after:
no goals