(    '(1 2 3)) = (1 2 3)
(car '(1 2 3)) = 1
(cdr '(1 2 3)) = (2 3)
(null? '(2 3)) = 0
(null?    '()) = 1

faculty(10) = 3628800
faculty(10) = 3628800
foobar = ("a" "bc" "def" "z")