Check if the metadata for the given item is present in
        the cache

        If the max_age attribute of this Cache is set to a nonzero value,
        entries older than the value of max_age in seconds will be ignored

        :type item_url: String or Item
        :param item_url: the URL of the item, or an Item object

        :rtype: Boolean
        :returns: True if the item is present, False otherwise

def has_item(self, item_url):
        """ Check if the metadata for the given item is present in
        the cache

        If the max_age attribute of this Cache is set to a nonzero value,
        entries older than the value of max_age in seconds will be ignored

        :type item_url: String or Item
        :param item_url: the URL of the item, or an Item object

        :rtype: Boolean
        :returns: True if the item is present, False otherwise


        """
        c = self.conn.cursor()
        c.execute("SELECT * FROM items WHERE url=?", (str(item_url),))
        row = c.fetchone()
        c.close()
        return self.__exists_row_not_too_old(row)