What would be necessary if the programmer wanted to re$-$use the same function object from above to average a second array? Say this one:

double b$[$MAX$2]=\{4\mathrm{.}4,9\mathrm{.}6,7\mathrm{.}2,9\mathrm{.}4,6\mathrm{.}3,5\mathrm{.}1\}$;

Carefully consider each of the three $(3)$ possible cases: non$-$template Sum, multiple typename Sum template, and nested template Sum.