Issue to make click on <a> tag in funcional test with selenium : i am to make a functional test and i need to make click on `<a>` tag, but i try some ways and really i don't know, i try with the commands in this url 
https://saucelabs.com/resources/articles/the-selenium-2018click2019-command, nothing has worked, if somebody can help me , i would apreciate it. Thanks.

import time
from selenium import webdriver
from unittest import TestCase

#driver = webdriver.Chrome('/path/to/chromedriver')  # Optional argument, if not specified will search path.
class GoToLogin(TestCase):
    
    driver = webdriver.Firefox()
    driver.get('http://192.168.56.101:8000/login/');
    #time.sleep(5) # Let the user actually see something!
    user_field = driver.find_element_by_id('id_username')
    user_field.send_keys('lruedc')
    
    password_field = driver.find_element_by_id('id_password')
    password_field.send_keys('lejoruca123')

    button_field = driver.find_element_by_id('btnlogin')
    button_field.click()
    
    #time.sleep(5) # Let the user actually see something!
    user_field.submit()
    self.driver.quit()