def current_spi_to_number(self):
        """
    Convert subpage & subitem to a integer

    * if page == 1, then return 0, since the item count is the true # of items
    * if page == 2, then return, page-1 * items_per_page, since we are
      returning the # of items on a full page.

    Args:
        * None

    Returns:
        * Integer - Which represents the number of items up to the page.
        """
        if self.slots['subpage'] == None:
            return self.sub_pi_to_number(0, 0)
        else:
            return self.sub_pi_to_number(self.slots['subpage'],
                                         self.slots['subitem'])
Convert subpage & subitem to a integer

    * if page == 1, then return 0, since the item count is the true # of items
    * if page == 2, then return, page-1 * items_per_page, since we are
      returning the # of items on a full page.

    Args:
        * None

    Returns:
        * Integer - Which represents the number of items up to the page.