anchor.diff:  (defpackage cl21.core.package
     (:use :cl)
     (:shadow :in-package
  +           :use-package
              :defpackage)
  +  (:import-from :cl21.core.readtable
  +                :get-package-readtable-options)
     (:import-from :named-readtables
                   :defreadtable
                   :find-readtable
                   :in-readtable)
  -  (:import-from :cl21.core.readtable
  -                :get-package-readtable-options)
  +  (:import-from :alexandria
  +                :ensure-list)
     (:export :package
              :export
              :find-symbol
  
positive.code:                      ,@readtable-options)
                     (in-readtable ,name))
                  '(in-readtable nil))))))
  
negative.code:        (cl:defpackage ,name ,@options)
       ,@(if (member :use options :key #'car)
             `((setf (gethash ,(intern (string name) :keyword) *package-use*)
                     ',(loop for use in (cdr (assoc :use options))
                             when (keywordp use)
                               collect use
                             else
                               collect (intern (string use) :keyword))))
             nil)))
  
  (defmacro in-package (name)
  