anchor.diff:    `(%%block ,@(@ [`(%= ,_. ,._.)]
                    (group args 2))))
   
  -(defun make-? (body)
  +(define-compiler-macro ? (&body body)
     (with (tests (group body 2)
            end   (car (last tests)))
       (unless body
  
positive.code:        ,@(? .end
              tests
              (+ (butlast tests) (list (. t end)))))))
  
  (define-compiler-macro ? (&body body)
    (make-? body))
  
  
  ;; TAGBODY
  
negative.code: ; tré – Copyright (c) 2006–2015 Sven Michael Klose <pixel@hugbox.org>
  
  (defvar *tagbody-replacements* nil)
  
  (defun init-compiler-macros ()
    (= *tagbody-replacements* nil))
  
  (defvar *compiler-macro-expander* (define-expander 'compiler :pre #'init-compiler-macros))
  
  (defmacro define-compiler-macro (name args &body x)
    (print-definition `(define-compiler-macro ,name ,args))
  