docs: def add_primary_text(self, item_url, primary_text):
          """ Add the given primary text to the cache database, updating
          the existing record if the primary text is already present
  
          :type item_url: String or Item
          :param item_url: the URL of the corresponding item, or an Item object
          :type primary_text: String
          :param primary_text: the item's primary text
  
  
          """
          c = self.conn.cursor()
          c.execute("DELETE FROM primary_texts WHERE item_url=?",
                        (str(item_url),))
          self.conn.commit()
          c.execute("INSERT INTO primary_texts VALUES (?, ?, ?)",
                    (str(item_url), primary_text, self.__now_iso_8601()))
          self.conn.commit()
          c.close()