original_string: public function getChallenge()
      {
          if (empty($this->_challenge))
          {
              $output = $this->postRequest(
                  'identification/securitytoken/challenge',
                  [
                      'useEasyLogin'        => false,
                      'generateEasyLoginId' => false,
                      'userId'              => $this->_username,
                  ]
              );
  
              if (!isset($output->links->next->uri))
                  throw new Exception('Cannot fetch control number. Check if the username is correct.', 10);
  
              $this->_challenge          = $output->challenge;
              $this->_useOneTimePassword = (bool)$output->useOneTimePassword;
          }
  
          return $this->_challenge;
      }
code: public function getChallenge()
      {
          if (empty($this->_challenge))
          {
              $output = $this->postRequest(
                  'identification/securitytoken/challenge',
                  [
                      'useEasyLogin'        => false,
                      'generateEasyLoginId' => false,
                      'userId'              => $this->_username,
                  ]
              );
  
              if (!isset($output->links->next->uri))
                  throw new Exception('Cannot fetch control number. Check if the username is correct.', 10);
  
              $this->_challenge          = $output->challenge;
              $this->_useOneTimePassword = (bool)$output->useOneTimePassword;
          }
  
          return $this->_challenge;
      }
code_tokens: public function getChallenge ( ) { if ( empty ( $ this -> _challenge ) ) { $ output = $ this -> postRequest ( 'identification/securitytoken/challenge' , [ 'useEasyLogin' => false , 'generateEasyLoginId' => false , 'userId' => $ this -> _username , ] ) ; if ( ! isset ( $ output -> links -> next -> uri ) ) throw new Exception ( 'Cannot fetch control number. Check if the username is correct.' , 10 ) ; $ this -> _challenge = $ output -> challenge ; $ this -> _useOneTimePassword = ( bool ) $ output -> useOneTimePassword ; } return $ this -> _challenge ; }
docstring: Fetch control number
  
  For security token with control number and response code.
  
  @return string|null Control number. Null if the security token only requires a generated one time code.
  @throws Exception
docstring_tokens: Fetch control number