original_string: public function login(string $redirect_url = '') {
          if ( null === $guid = $this->getGuidFromQuery() ) {
              header( 'Location: ' . $this->getLoginUrl($redirect_url) );
              exit();
          } else {
              return $this->verify($guid);
          }
      }
code: public function login(string $redirect_url = '') {
          if ( null === $guid = $this->getGuidFromQuery() ) {
              header( 'Location: ' . $this->getLoginUrl($redirect_url) );
              exit();
          } else {
              return $this->verify($guid);
          }
      }
code_tokens: public function login ( string $ redirect_url = '' ) { if ( null === $ guid = $ this -> getGuidFromQuery ( ) ) { header ( 'Location: ' . $ this -> getLoginUrl ( $ redirect_url ) ) ; exit ( ) ; } else { return $ this -> verify ( $ guid ) ; } }
docstring: Login and return the username
  
  @param $redirect_url string  从CAS登录后跳转的URL，用于接收guid ($redirect_url?guid=...)
  
  @return string               返回登录用户名
docstring_tokens: Login and return the username