wp-includes/SimplePie/src/Cache/Memcache.php:123Set the last modified time to the current time
bool public function touch() { $data = $this->cache->get($this->name); if ($data !== false) { return $this->cache->set($this->name, $data, MEMCACHE_COMPRESSED, (int) $this->options['extras']['timeout']); } return false; }Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/SimplePie/src/Cache/Memcache.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.