Xpressengine\Keygen\Keygen::generate PHP Method

    public function generate()
    {
        $version = $this->getMode();
        $method = 'createIdVersion' . $version;
        if (!method_exists($this, $method)) {
            throw new UnknownGeneratorVersionException(['version' => $version]);
        }
        try {
            if (in_array($version, [3, 5])) {
                return $this->{$method}($this->config['namespace']);
            }
            return $this->{$method}();
        } catch (UnsatisfiedDependencyException $e) {
            throw $e;
        }
    }

 /**
  * Generate new key
  *
  * @return string
  */
 protected function generateNewId()
 {
     $newId = substr($this->keygen->generate(), 0, 8);
     if (!preg_match('/[^0-9]/', $newId)) {
         $newId = $this->generateNewId();
     }
     return $newId;
 }