anchor.diff:    (let form (tree-transform-compile-r (tree-transform-match trn) trn)
       (= (tree-transform-compiled-match trn)
         (eval (macroexpand `#'((e trn)
  -        (& ,@form)))))))
  +                               (& ,@form)))))))
   
   (defun tree-transform! (trn e)
     (when (cons? e)
  
positive.code:     (setq ,name
        (make-tree-transform :placeholders ,placeholders
                             :match ,match
  			   :conversion #'((&key ,@(cadr placeholders))
  					 ,conversion)))
      (tree-transform-compile ,name)))
  
  (defun tree-transform-conversion-args (trn)
  
negative.code: ;;;; tré – Copyright (c) 2005,2011–2012 Sven Michael Klose <pixel@copei.de>
  ;;;;
  ;;;; Tree transformation
  ;;;;
  