FileCookieJar has not attribute "_self_load"

[Dragos]

I am trying to make a testing script to load/save cookies to a file
with FileCookieJar, but it results in this error: FileCookieJar has
not attribute "_self_load"

This is my script:

import urllib.request, urllib.parse,http.cookiejar
url="http://localhost/test.php"
cs=http.cookiejar.FileCookieJar()
cs.load("cookies.txt",ignore_discard=False, ignore_expires=False)
opener=urllib.request.build_opener(urllib.request.HTTPCookieProcessor
(cs))
y=opener.open(url)
print(y.read())

Thanks for helping.