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

State before:
x : Pos
⊢ x * 1 = x
Tactic:
by_toNat
State after:
x : Pos
⊢ x.toNat * 1 = x.toNat

State before:
x : Pos
⊢ x.toNat * 1 = x.toNat
Tactic:
exact Nat.mul_one _
State after:
no goals