Fxmlrpc\Client::call PHP Method

    public function call($methodName, array $params = [])
    {
        if (!is_string($methodName)) {
            throw InvalidArgumentException::expectedParameter(0, 'string', $methodName);
        }
        $params = array_merge($this->prependParams, $params, $this->appendParams);
        $payload = $this->serializer->serialize($methodName, $params);
        $response = $this->transport->send($this->uri, $payload);
        return $this->parser->parse($response);
    }

 /**
  * {@inheritdoc}
  */
 public function execute()
 {
     $results = $this->client->call('system.multicall', [$this->calls]);
     foreach ($results as $index => $result) {
         $this->processResult($this->handlers[$index], $result);
     }
     return $results;
 }