'Check if a caption line focused
Arguments:
line_number (int): caption line number'

def is_caption_line_focused(self, line_number):

    caption_line_selector = ".subtitles    li    span[data-index='{index}']".format(index=(line_number - 1))
    caption_container = self.q(css=caption_line_selector).results[0].find_element_by_xpath('..')
    return ('focused' in caption_container.get_attribute('class').split())
