Item::get_id( boolean $hash = false, string|false $fn = 'md5' ): string|null

216    public function get_id($hash = false, $fn = 'md5')217    {218        if (!$hash) {219            if ($return = $this->get_item_tags(\SimplePie\SimplePie::NAMESPACE_ATOM_10, 'id')) {220                return $this->sanitize($return[0]['data'], \SimplePie\SimplePie::CONSTRUCT_TEXT);221            } elseif ($return = $this->get_item_tags(\SimplePie\SimplePie::NAMESPACE_ATOM_03, 'id')) {222                return $this->sanitize($return[0]['data'], \SimplePie\SimplePie::CONSTRUCT_TEXT);223            } elseif ($return = $this->get_item_tags(\SimplePie\SimplePie::NAMESPACE_RSS_20, 'guid')) {224                return $this->sanitize($return[0]['data'], \SimplePie\SimplePie::CONSTRUCT_TEXT);225            } elseif ($return = $this->get_item_tags(\SimplePie\SimplePie::NAMESPACE_DC_11, 'identifier')) {226                return $this->sanitize($return[0]['data'], \SimplePie\SimplePie::CONSTRUCT_TEXT);227            } elseif ($return = $this->get_item_tags(\SimplePie\SimplePie::NAMESPACE_DC_10, 'identifier')) {228                return $this->sanitize($return[0]['data'], \SimplePie\SimplePie::CONSTRUCT_TEXT);229            } elseif (isset($this->data['attribs'][\SimplePie\SimplePie::NAMESPACE_RDF]['about'])) {230                return $this->sanitize($this->data['attribs'][\SimplePie\SimplePie::NAMESPACE_RDF]['about'], \SimplePie\SimplePie::CONSTRUCT_TEXT);231            }232        }233        if ($fn === false) {234            return null;235        } elseif (!is_callable($fn)) {236            trigger_error('User-supplied function $fn must be callable', E_USER_WARNING);237            $fn = 'md5';238        }239        return call_user_func(240            $fn,241            $this->get_permalink().$this->get_title().$this->get_content()242        );243    }