Page-object model is a pattern that you can apply it to develop efficient automation framework. With page-model, it is possible to minimize maintanecy cost. Basically page-object means that your every page is inhereted from a base class which includes basic functionality for every page.

base.py

from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.common.action_chains import ActionChains

# this Base class is serving basic attributes for every single page inherited from Page class

class Page(object):
    def __init__(self, driver, base_url='http://www.app.com/'):
        self.base_url = base_url
        self.driver = driver
        self.timeout = 30
 
    def find_element(self, *locator):
        return self.driver.find_element(*locator)
 
    def open(self,url):
        url = self.base_url + url
        self.driver.get(url)
        
    def get_title(self):
        return self.driver.title
        
    def get_url(self):
        return self.driver.current_url
    
    def hover(self, *locator):
        element = self.find_element(*locator)
        hover = ActionChains(self.driver).move_to_element(element)
        hover.perform()

locators.py

from selenium.webdriver.common.by import By

# for maintainability we can seperate web objects by page name

class MainPageLocatars(object):
  LOGO          = (By.ID, 'nav-logo')
  ACCOUNT       = (By.ID, 'nav-link-yourAccount')
  SIGNUP        = (By.CSS_SELECTOR, '#nav-flyout-ya-newCust > a')
  LOGIN         = (By.CSS_SELECTOR, '#nav-flyout-ya-signin > a')
  SEARCH        = (By.ID, 'twotabsearchtextbox')
  SEARCH_LIST   = (By.ID, 's-results-list-atf')

class LoginPageLocatars(object):
  EMAIL         = (By.ID, 'ap_email')
  PASSWORD      = (By.ID, 'ap_password')
  SUBMIT        = (By.ID, 'signInSubmit-input')
  ERROR_MESSAGE = (By.ID, 'message_error')

pages.py

from selenium import webdriver
from selenium.webdriver.common.keys import Keys
from base import Page
from locators import *
import users
from selenium.webdriver.support.ui import WebDriverWait


# Page opjects are written in this module.
# Depends on the page functionality we can have more functions for new classes

class MainPage(Page):
    def check_page_loaded(self):
        return True if self.find_element(*MainPageLocatars.LOGO) else False

    def search_item(self, item):
        self.find_element(*MainPageLocatars.SEARCH).send_keys(item)
        self.find_element(*MainPageLocatars.SEARCH).send_keys(Keys.ENTER)
        return self.find_element(*MainPageLocatars.SEARCH_LIST).text
        
    def click_sign_up_button(self):
        self.hover(*MainPageLocatars.ACCOUNT)
        self.find_element(*MainPageLocatars.SIGNUP).click()
        return SignUpPage(self.driver)

    def click_sign_in_button(self):
        self.hover(*MainPageLocatars.ACCOUNT)
        self.find_element(*MainPageLocatars.LOGIN).click()
        return LoginPage(self.driver)

class LoginPage(Page):
    def enter_email(self, user):
        self.find_element(*LoginPageLocatars.EMAIL).send_keys(users.get_user(user)["email"])

    def enter_password(self, user):
        self.find_element(*LoginPageLocatars.PASSWORD).send_keys(users.get_user(user)["password"])

    def click_login_button(self):
        self.find_element(*LoginPageLocatars.SUBMIT).click()

    def login(self, user):
        self.enter_email(user)
        self.enter_password(user)
        self.click_login_button()

    def login_with_valid_user(self, user):
        self.login(user)
        return HomePage(self.driver)

    def login_with_in_valid_user(self, user):
        self.login(user)
        return self.find_element(*LoginPageLocatars.ERROR_MESSAGE).text    

class HomePage(Page):
    pass
    
class SignUpPage(Page):
    pass

testPages.py

import unittest
from selenium import webdriver
from pages import *
from testCases import test_cases
from locators import *
from selenium.webdriver.common.by import By

# I am using python unittest for asserting cases.
# In this module, there should be test cases.
# If you want to run it, you should type: python <module-name.py>

class TestPages(unittest.TestCase):

    def setUp(self):
        self.driver = webdriver.Chrome()
        #self.driver = webdriver.Firefox()
        self.driver.get("http://www.amazon.com")

    def test_page_load(self):
        print "\n" + str(test_cases(0))
        page = MainPage(self.driver)
        self.assertTrue(page.check_page_loaded())

    def test_search_item(self):
        print "\n" + str(test_cases(1))
        page = MainPage(self.driver)
        search_result = page.search_item("Nexus 5")
        self.assertIn("Nexus 5", search_result)

    def test_sign_up_button(self):
        print "\n" + str(test_cases(2))
        page = MainPage(self.driver)
        signUpPage = page.click_sign_up_button()
        self.assertIn("ap/register", signUpPage.get_url())

    def test_sign_in_button(self):
        print "\n" + str(test_cases(3))
        page = MainPage(self.driver)
        loginPage = page.click_sign_in_button()
        self.assertIn("ap/signin", loginPage.get_url())

    def test_sign_in_with_valid_user(self):
        print "\n" + str(test_cases(4))
        mainPage = MainPage(self.driver)
        loginPage = mainPage.click_sign_in_button()
        result = loginPage.login_with_valid_user("valid_user")
        self.assertIn("yourstore/home", result.get_url())

    def test_sign_in_with_in_valid_user(self):
        print "\n" + str(test_cases(5))
        mainPage = MainPage(self.driver)
        loginPage = mainPage.click_sign_in_button()
        result = loginPage.login_with_in_valid_user("invalid_user")
        self.assertIn("There was a problem with your request", result)

    def tearDown(self):
        self.driver.close()

if __name__ == "__main__":
    suite = unittest.TestLoader().loadTestsFromTestCase(TestPages)
    unittest.TextTestRunner(verbosity=2).run(suite)