def grab_selenium_driver(driver_name=None):
    """
    pip install selenium -U
    """
    from selenium import webdriver
    if driver_name is None:
        driver_name = 'firefox'
    if driver_name.lower() == 'chrome':
        grab_selenium_chromedriver()
        return webdriver.Chrome()
    elif driver_name.lower() == 'firefox':
        # grab_selenium_chromedriver()
        return webdriver.Firefox()
    else:
        raise AssertionError('unknown name = %r' % (driver_name,))