code: private function requestImpl(string $requestType)
      {
          if ($requestType == 'HEAD') {
              $this->setTimeout(1); // Don't wait too long on simple head
          }
          
          $ms = $this->prepareRequest($requestType);
          
          $ms = $this->appendPayloadToRequest($ms);
          
          if (! $this->isConnected()) {
              $this->connect();
          }
          
          while ($ms->ready()) {
              $this->write($ms->read(1024));
          }
          
          $this->retrieveAndParseResponse($requestType);
          
          if ($this->getHeader('Connection') == 'close') {
              $this->disconnect();
          }
      }
docs: Perform the request
  
  @param string $requestType