Return read-only copy

		:return: WHTTPCookieJar

def ro(self):
		""" Return read-only copy

		:return: WHTTPCookieJar
		"""
		ro_jar = WHTTPCookieJar()
		for cookie in self.__cookies.values():
			ro_jar.add_cookie(cookie.ro())
		ro_jar.__ro_flag = True
		return ro_jar