python+selenium UI自动化不同浏览器之间的切换

class register():
    ROBOT_LIBRARY_SCOPE = 'GLOBAL'
    def __init__(self):
        pass
    # m默认打开chrome
    def open_browser(self,browser='chrome'):
        try:
            if browser == 'chrome':
                self.driver = webdriver.Chrome(get_chrome_webdriver)
                self.driver.get(LoginUrl)
                self.driver.implicitly_wait(20)
                self.driver.maximize_window()
                return  self.driver
            elif browser == 'firefox':
                self.driver = webdriver.Firefox()
                self.driver.get(LoginUrl)
                self.driver.implicitly_wait(20)
                self.driver.maximize_window()
                return  self.driver
            elif browser == 'ie':
                self.driver = webdriver.Ie()
                self.driver.get(LoginUrl)
                self.driver.implicitly_wait(20)
                self.driver.maximize_window()
                return self.driver
            else:
                print("not found browser! you can enter 'firefox','chrome' or 'ie'")
        except Exception as msg:
            print("open browser error:%s" % msg)

if __name__ == '__main__':
    foo = register()

    driver_chrome = foo.open_browser()
    print("open browser:%s" % driver_chrome.name)
    print(driver_chrome.title)

    driver_firefox = foo.open_browser('firefox')
    print("open browser:%s" % driver_firefox.name)
    print(driver_firefox.title)