code: protected function getUrl()
      {
          $domain = $this->urls['domain'];
  
          $apiVersion = $this->urls['api'];
  
          $jsonExt = '.json';
  
          if (isset($this->withMedia) && $this->withMedia === true) {
              $domain = $this->urls['upload'];
          }
  
          if ($this->call === 'oauth/request_token' || $this->call === 'oauth/access_token') {
              $apiVersion = '';
              $jsonExt = '';
          }
  
          return $domain . $apiVersion . $this->call . $jsonExt;
      }
docs: Getting full URL from a Twitter resource
  
  @return string  Full URL