code: func filterHeaders(headers http.Header, iterator headerIterator) {
  	for k, v := range headers {
  		// Skip sensitive headers
  		if k == "Authorization" || k == "Cookie" {
  			iterator(k, []string{"*****"})
  			continue
  		}
  		iterator(k, v)
  	}
  }
docs: // filterHeaders iterates through the headers skipping hidden headers.
  // It calls the given iterator for each header name/value pair. The values are serialized as
  // strings.