anchor.diff:      (set-current-buffer buffer)
       buffer))
   
  +(defun assert-package-manager ()
  +  (unless (ospama:manager)
  +    (let ((message "No supported package manager detected."))
  +      (echo message)
  +      (error message))))
  +
   (define-command describe-os-package ()
     "Show description of select packages."
  +  (assert-package-manager)
     (let* ((packages (prompt-minibuffer
                       :suggestion-function (os-package-suggestion-filter)
                       :input-prompt "Describe OS package(s)"
  
positive.code:                       :buffer (make-internal-buffer :title "*OS packages*")))))
      (html-set
       (markup:markup
              (:style (style buffer))
              (:h1 "Package files")
              (:ul
               (loop for package-or-output in packages-or-outputs
                     collect (markup:markup*
                              `(:li ,(object-string package-or-output)
                                    (:ul
                                     ,@(mapcar (lambda (file)
                                                 `(:li ,(if (viewable-file-type-p file)
                                                            `(:a :href ,file ,file)
                                                            file)))
                                               (ospama:list-files (list package-or-output)))))))))
       buffer)
      (set-current-buffer buffer)
      buffer))
  
negative.code: 
  (define-command install-os-package ()
    "Install select packages."
    (assert-package-manager)
    ;; TODO: Allow profile creation.  Need multi-source support for that?
    (let* ((profile (prompt-minibuffer
                     :suggestion-function (os-profile-suggestion-filter)
  