def proxy
      if @proxy.nil?
        path = "/org/freedesktop/DBus"
        dest = "org.freedesktop.DBus"
        pof = DBus::ProxyObjectFactory.new(
          DBUSXMLINTRO, self, dest, path,
          api: ApiOptions::A0
        )
        @proxy = pof.build["org.freedesktop.DBus"]
      end
      @proxy
    end
def proxy
      if @proxy.nil?
        path = "/org/freedesktop/DBus"
        dest = "org.freedesktop.DBus"
        pof = DBus::ProxyObjectFactory.new(
          DBUSXMLINTRO, self, dest, path,
          api: ApiOptions::A0
        )
        @proxy = pof.build["org.freedesktop.DBus"]
      end
      @proxy
    end
Set up a ProxyObject for the bus itself, since the bus is introspectable.
 @return [ProxyObject] that always returns an array
   ({DBus::ApiOptions#proxy_method_returns_array})
 Returns the object.