anchor.diff:  (defclass signal-handler (handler)
     ())
   
  -(defun register-dbus-signal-handler (object-name handler-name name-string interface parameter-types handler)
  +(defun register-dbus-signal-handler (object-name handler-name name-string interface parameter-types parameter-names handler)
     (check-type handler-name symbol)
     (check-type name-string string)
     (check-type interface string)
  
positive.code:                          :name name-string
                           :interface interface
                           :input-signature parameter-types
                           :output-signature return-types
                           :function handler))
      (list object-name method-name)))
  
negative.code:                          :name name-string
                           :interface interface
                           :input-signature parameter-types
                           :input-names parameter-names
                           :function handler))
      (list object-name handler-name)))
  
  