Claim:There is a unique function with an empty domain

Claim (see proof):

For any set [math]A [/math], there is a unique function [math]f : \href{/cs2800/wiki/index.php?title=%5Cemptyset&action=edit&redlink=1}{\emptyset} \href{/cs2800/wiki/index.php/%5Cto}{\to} A [/math].