R4RS Appendix  (define-syntax <keyword> <transformer>)  ==>  unspecific

Syntax: The <keyword> is an identifier, and <transformer> should be
an instance of SYNTAX-RULES.

Semantics: The top-level syntactic environment is extended by binding
the <keyword> to the specified transformer.

(define-syntax let*
  (syntax-rules ()
    ((let* () body1 body2 ...)
     (let () body1 body2 ...))
    ((let* ((name1 val1) (name2 val2) ...)
       body1 body2 ...)
     (let ((name1 val1))
       (let* ((name2 val2) ...)
         body1 body2 ...)))))
