anchor.diff:  
   (defun backquote-cons-1 (x)
     (?
  -    (atom x)                (backquote-cons-atom x)
  -    (atom x.)               `(cons ,(backquote-cons-atom x.)
  +    (atom x)                (quote-literal x)
  +    (atom x.)               `(cons ,(quote-literal x.)
                                      ,(backquote-cons-2 .x))
       (quasiquote? x.)        (backquote-cons-quasiquote x)
       (quasiquote-splice? x.) (backquote-cons-quasiquote-splice x)
  
positive.code:                   ,(backquote-cons-1 .x))
            (copy-tree (cadr x.)))))
  
  (defun backquote-cons-atom (x)
    (? (| (not x)
          (number? x)
          (string? x)
  
negative.code: ;;;;; tré – Copyright (c) 2006–2013 Sven Michael Klose <pixel@copei.de>
  
  (defun backquote-cons-quasiquote (x)
    (? (any-quasiquote? (cadr x.))
  