I won't use it, its indentation is very off.
take here: b is the body of the lambda function, but its indented as if its the body of the `letrec`
(syntax (letrec ((f (lambda (a ...)
b
...)))
or here
(define-syntax aif
(lambda (x)
(syntax-case x ()
((\_ test then else)
(with-syntax ((it (datum->syntax x 'it)))
\#'(let ((it test))
(if it then else)))))))