code: func (h *RequestHeader) VisitAllInOrder(f func(key, value []byte)) {
  	h.parseRawHeaders()
  	var s headerScanner
  	s.b = h.rawHeaders
  	s.disableNormalizing = h.disableNormalizing
  	for s.next() {
  		if len(s.key) > 0 {
  			f(s.key, s.value)
  		}
  	}
  }
docs: // VisitAllInOrder calls f for each header in the order they were received.
  //
  // f must not retain references to key and/or value after returning.
  // Copy key and/or value contents before returning if you need retaining them.
  //
  // This function is slightly slower than VisitAll because it has to reparse the
  // raw headers to get the order.