anchor.diff:    (:implementation ccl
       (ql-ccl:delete-directory pathname)))
   
  +(defimplementation (delete-directory-tree :qualifier :around) (pathname)
  +  (if (directoryp pathname)
  +      (call-next-method)
  +      (progn
  +        (warn "delete-directory-tree - not a directory, ~
  +               deleting anyway -- ~s" pathname)
  +        (delete-file pathname))))
  +
  
positive.code:   (:implementation sbcl
      (ql-sbcl:rmdir entry)))
  
  (definterface delete-directory-tree (pathname)
    (:documentation "Delete the directory tree rooted at PATHNAME.")
    (:implementation t
  
negative.code: (defvar *wild-relative*
    (make-pathname :directory '(:relative :wild)))
  
  (definterface directoryp (entry)
    (:documentation "Return true if ENTRY refers to a directory.")
    (:implementation t
      (not (or (pathname-name entry)
               (pathname-type entry))))
    (:implementation allegro
      (ql-allegro:file-directory-p entry))
    (:implementation lispworks
      (ql-lispworks:file-directory-p entry)))
  
  (definterface directory-entries (directory)
    (:documentation "Return all directory entries of DIRECTORY as a
    list, or NIL if there are no directory entries. Excludes the \".\"
  