code: public function invokeRpcCall($method, $arguments = [])
      {
          if (!is_null($this->namespace)) {
              $method = $this->namespace . '.' . $method;
          }
  
          $body = XmlRpcBuilder::createRequest($method, $arguments);
  
          $guzzle = new \GuzzleHttp\Client();
  
          $this->getLogger()->info("sending request for $method to {$this->url}");
          $this->getLogger()->debug(
              "sending request for $method to {$this->url}, with parameters: " . print_r($arguments, true)
          );
  
          $response = $guzzle->post(
              $this->url,
              [
                  'body' => $body,
                  'headers' => [
                      'User-Agent' => 'Devedge\XmlRpc\Client/' .self::$version,
                      'Content-Type' => 'text/xml'
                  ]
              ]
          );
  
          // if we have a fault, we will throw an exception
          if ($response->xml()->fault->count() > 0) {
              $this->logger->warning("serverside error occured, details: " . $response->getBody());
              throw XmlRpcParser::parseFault($response->xml()->fault);
          }
  
          // responses always have only one param
          return array_shift(XmlRpcParser::parseParams($response->xml()->params));
      }
docs: invoke a call to the RPC server
  @param string $method
  @param array $arguments
  @return array