in racket please$-$ Most LISP dialects have an if form that given $($if aexp texp fexp$)$ will be texp when aexp is #t and fexp is false. Rewrite the following expression to use if:

$($cond $(($null$?$ l$)$ nil$)($t $($or $($eq$?($car l$)$ a$)($member$?$ a $($cdr l$)))))$