code: public function authenticate($accountKey, $uniqueUserId, $authMethod = null)
      {
          if (null === $authMethod) {
              $authMethod = self::AUTH_HTTP_TOKEN;
          }
  
          $this->getHttpClient()->authenticate($accountKey, $uniqueUserId, $authMethod);
      }
docs: Authenticate a user for all next requests.
  
  @param string      $accountKey   LTA DataMall AccountKey
  @param string      $uniqueUserId UniqueUserID generated from DataMall Tool
  @param null|string $authMethod   One of the AUTH_* class constants