Mellin Transform of Power Times Function

Theorem
Let $t^n: \R \to \R$ be $t$ to the $n$th power for some $n \in \N_{\ge 0}$.

Let $\MM$ be the Mellin transform.

Then:
 * $\map {\MM \set {t^n \map f t} } s = \map {\MM \set {\map f t} } {s + n}$

given that both transforms exist.