code: public function fetch(string $key, $default = null)
      {
          if (isset($_SERVER[$key])) {
              return $_SERVER[$key];
          } else {
              $key = 'HTTP_' . $key;
              return $_SERVER[$key] ?? $default;
          }
      }
docs: Returns a SERVER parameter by name.
  
  @param string $key
  @param mixed|null $default The default value if the parameter key does not exist
  @return mixed|null