code: func (req *Request) GetMultipartForm() (ServerMultipartForm, error) {
  	if form, err := req.In.Get(HTTP_MULTIPART_FORM); err != nil {
  		return nil, err
  	} else if values, found := form.(ServerMultipartForm); found {
  		return values, nil
  	}
  	return nil, FORM_NOT_FOUND
  }
docs: // Return a multipart form