dialogs = [i.get_attribute('data-list-id') for i in
self.find_elements_by_xpath('//ul[@id="im_dialogs"]/li[contains(@class, "nim-dialog_unread ")]')]
//ul[@id="im_dialogs"]/li[contains(@class, "nim-dialog_unread ")]/@data-list-id
string(//ul[@id="im_dialogs"]/li[contains(@class, "nim-dialog_unread ")]/@data-list-id)