anchor.diff:  (defun backquote-1 (x)
     (?
       (atom x)                (quote-literal x)
  -    (atom x.)               `(cons ,(quote-literal x.)
  -                                   ,(backquote-2 .x))
  +    (atom x.)               `(. ,(quote-literal x.)
  +                                ,(backquote-2 .x))
       (quasiquote? x.)        (backquote-quasiquote x)
       (quasiquote-splice? x.) (backquote-quasiquote-splice x)
  -    `(cons ,(backquote-1 x.)
  -           ,(backquote-2 .x))))
  +    `(. ,(backquote-1 x.)
  +        ,(backquote-2 .x))))
   
   (defun simple-quote-expand (x)
     (? (atom x)
        (quote-literal x)
  -     `(cons ,(simple-quote-expand x.)
  -            ,(simple-quote-expand .x))))
  +     `(. ,(simple-quote-expand x.)
  +         ,(simple-quote-expand .x))))
   
   (defun backquote-expand (l)
     (tree-walk l
  
positive.code:          `(%nconc (copy-list ,(let tr *transpiler*
                                  (? (transpiler-assert? tr)
                                     (frontend-macroexpansions `(aprog1 ,(cadr x.)
                                                                  (| (list? !) (error ",@ expects a list instead of ~A." !))))
                                     (cadr x.))))
                     ,(backquote-1 .x))
           (cadr x.))))
  
negative.code: ;;;;; tré – Copyright (c) 2006–2014 Sven Michael Klose <pixel@copei.de>
  
  (defun backquote-quasiquote (x)
    (? (any-quasiquote? (cadr x.))
       `(. ,(backquote-1 (cadr x.))
           ,(backquote-1 .x))
       `(. ,(cadr x.)
           ,(backquote-1 .x))))
  
  (defun backquote-quasiquote-splice (x)
    (? (any-quasiquote? (cadr x.))
  