code: func (s *Header) modifyRequestHeaders(req *http.Request) {
  	// Loop through Custom request headers
  	for header, value := range s.headers.CustomRequestHeaders {
  		if value == "" {
  			req.Header.Del(header)
  		} else {
  			req.Header.Set(header, value)
  		}
  	}
  }
docs: // modifyRequestHeaders sets or deletes request headers.