Use Proxy with Authorization in Firefox with Selenium in Python

Question

How to provide Username and Password to a proxy server in Firefox with selenium in python?

I tried the code below but the IP address doesn't change. I check the proxy setting in Firefox, it shows that only http proxy is changed, but not https.

proxy = {'host': '111.111.111.11', 
         'port': 8080, 
         'usr': USERNAME, 
         'pwd': PASSWORD
         }
profile = webdriver.FirefoxProfile()
profile.set_preference("network.proxy.type", 1)
profile.set_preference("network.proxy.http", proxy['host'])
profile.set_preference("network.proxy.https", proxy['host'])
profile.set_preference("network.proxy.http_port", proxy['port'])
profile.set_preference("network.proxy.username", proxy['usr'])
profile.set_preference("network.proxy.password", proxy['pwd'])
profile.update_preferences()
driver = webdriver.Firefox(firefox_profile=profile)
driver.get('https://whatismyipaddress.com')

I see a solution for ChromeDriver (but I don't test it because I can only use Firefox):

chrome_options = webdriver.ChromeOptions()
chrome_options.add_argument('--proxy-server=196.19.8.80:8000')
chrome_options.add_argument('--proxy-auth=yjd5Rn:29apJZ')
chrome = webdriver.Chrome(chrome_options=chrome_options)
chrome.get("http://whatismyipaddress.com")

As you can see, ChromeOptions have '--proxy-auth=yjd5Rn:29apJZ' argument.

Could anyone tell me how to use proxy and provide authorization to proxy server in Firefox with Selenium and in python? Thanks in advance!

Below is the login page from the proxy server: