anchor.diff:  (define-class scheme ()
     ((name (error "Scheme must have a name/scheme")
            :documentation "Scheme/name of the internal scheme.
  -E.g. \"gopher\", \"irc\".")
  +For instance, \"gopher\", \"irc\".")
      (callback
       nil
       :type (or null (function (url-designator buffer) t))
  
positive.code:     :documentation "Local schemes are not accessible to the pages of other schemes.")
     (local-access-p
      nil
      :documentation "Local access allowed schemes can load resources from other schemes.
  
  QtWebEngine-specific.")
     (no-access-p
      nil
      :documentation "No-access schemes cannot access pages with any other scheme.
  
  Has slightly different behavior between ports.")
     (display-isolated-p
      nil
      :documentation "Display isolated schemes cannot be displayed by other schemes.
  
  WebKitGTK-specific.")
     (service-workers-allowed-p
  
negative.code:   (typep object '(and sequence (not string))))
  
  (defun scalar-p (object)
    ;; REVIEW: List direct T subclasses instead?
    "Return true if OBJECT is of one of the following types:
  - symbol,
  - character,
  - string,
  