wp-includes/SimplePie/src/SimplePie.php:725Used for converting object to a string
public function __toString() { return md5(serialize($this->data)); }One change between 6.7.7 and 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
none to string.verified against sourcesrc/wp-includes/SimplePie/src/SimplePie.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.