Consider the following Scheme function fun:

$($DEFINE $($fun k x$)$

$($COND

NULL? $x$

$))=((k(CARx)$

$($ELSE $($fun k $($CDR x$)))$

$)$

In each of the following cases, give the value of the expression and explain how it was derived.

$($a$)($fun $($:$8^{\text{'}}()\}$

$($b$)($fun $8\text{'}(48922))$