code: public function login($subject)
      {
          /** @var HasLoginToken */
          $caller = $this->identifier->identify($subject);
  
          if ($this->authenticator->authenticate($subject, $caller)) {
              $this->driver->setLoginToken($caller->getLoginToken());
              $this->currentCaller = $caller;
  
              return true;
          }
  
          return false;
      }
docs: Logs a subject in
  
  @param mixed $subject