public function gettext_select_plural_form($count)
    {
        if (!isset($this->_gettext_select_plural_form)
            || is_null($this->_gettext_select_plural_form)) {
            list($nplurals, $expression) = $this->nplurals_and_expression_from_header($this->get_header('Plural-Forms'));
            $this->_nplurals = $nplurals;
            $this->_gettext_select_plural_form = $this->make_plural_form_function($nplurals, $expression);
        }

        return call_user_func($this->_gettext_select_plural_form, $count);
    }