anchor.diff:    (iter (for (k v . rest) on env by #'cddr)
   	(collect k into keys)
   	(collect v into values)
  -	(finally 
  +	(finally
   	 (progv keys values
   	   ;; pass env to funcall to assist debugging
   	   (return (funcall tal-fn env))
  
positive.code:    file is actually contained in those directories
     i.e. prevent escaping the bounds via ../../../"
    (let* ((name (pathname name))
  	 (dir-list (pathname-directory name))
  	 (rel-p (or (null dir-list)
  		    (eql :relative (first dir-list)))))
  
      (when (and (not rel-p)
  	       (not (probe-file name)))
        ;;absolute name for missing file
        (return-from find-file-in-directories nil))
  
      (dolist (root (alexandria:ensure-list root-directories))
        (let ((root (pathname root))
  	    (root-dirs (pathname-directory root)))
  	(if rel-p
  	    (let ((candidate (probe-file (eliminate-..-in-path
                                            (merge-pathnames name root)))))
  	      (when (and candidate
                           ; ensure it is a file and not a directory.
                           (pathname-name candidate))
  		;;found a file, now check that it is in the roots. 
  		(return-from find-file-in-directories
  		  (find-file-in-directories candidate root-directories))))
  	    
  	    ;; we have an absolute file path, if root is absolute, we
  	    ;; should verify that the file is rooted in this directory
  	    ;; if the root is relative, assume we did stuff correctly
  	    ;; above
  	    (when (or (not (eql :absolute (car root-dirs)))
  		      (starts-with dir-list root-dirs :test #'equal))
  	      (return-from find-file-in-directories (probe-file name))))))))
  
  ;;;;;;;;;;;;;;; END BASIC UTILS
  
  
negative.code: 
  
  ;; Copyright (c) 2002-2005, Edward Marco Baringer
  ;; All rights reserved.
  ;;
  ;; Redistribution and use in source and binary forms, with or without
  ;; modification, are permitted provided that the following conditions are
  ;; met:
  ;;
  ;;  - Redistributions of source code must retain the above copyright
  ;;    notice, this list of conditions and the following disclaimer.
  ;;
  ;;  - Redistributions in binary form must reproduce the above copyright
  ;;    notice, this list of conditions and the following disclaimer in the
  ;;    documentation and/or other materials provided with the distribution.
  