def format_item(item, xmlns, key):
    """
        Format a rss item and return data.

        This properly format a rss item regarding the xmlns attribute and a key.
        It returns the data of the item regarding it's key.

        :param item: A rss item
        :param xmlns: XML namespace of the rss feed
        :param key: The key to format
        :type item: WebDriver
        :type xmlns: str
        :type key: str
        :return: The item content
        :rtype: str
    """
    formated_key = key
    if xmlns:
        formated_key = xmlns + key
    data = item.find(formated_key)
    if key == 'link' and xmlns:
        return data.attrib.get('href')
    else:
        return ''.join(data.itertext())