public function getAccountBalance()
 {
     $request = new \stdClass();
     $request->User = $this->getUsername();
     $request->Password = $this->getPassword();
     $result = $this->informationClient->QueryAccountBalance($request);
     if (is_object($result)) {
         return $result->QueryAccountBalanceResult->Value;
     }
     return NULL;
 }