anchor.diff:  (export-always 'uninstall-command)
   (defgeneric uninstall-command (manager profile)
     (:method ((manager manager) profile)
  +    (declare (ignorable profile))
       (error "Unspecified manager method"))
     (:documentation "Return the package manager command (as a list of string)
   to uninstall packages"))
  
positive.code: (export-always 'manager-find-os-package)
  (defgeneric manager-find-os-package (manager name)
    (:method ((manager manager) name)
      (error "Unspecified manager method"))
    (:documentation "Return the package matching NAME."))
  
  
negative.code: (export-always 'install-manifest-command)
  (defgeneric install-manifest-command (manager profile)
    (:method ((manager manager) profile)
      (declare (ignorable profile))
      (error "Unspecified manager method"))
    (:documentation "Return the package manager command (as a list of string)
  to install a manifest."))
  