code: func (h *Handler) handleGetFragmentData(w http.ResponseWriter, r *http.Request) {
  	// Read shard parameter.
  	q := r.URL.Query()
  	shard, err := strconv.ParseUint(q.Get("shard"), 10, 64)
  	if err != nil {
  		http.Error(w, "shard required", http.StatusBadRequest)
  		return
  	}
  	// Retrieve fragment data from holder.
  	f, err := h.api.FragmentData(r.Context(), q.Get("index"), q.Get("field"), q.Get("view"), shard)
  	if err != nil {
  		http.Error(w, err.Error(), http.StatusNotFound)
  		return
  	}
  	// Stream fragment to response body.
  	if _, err := f.WriteTo(w); err != nil {
  		h.logger.Printf("error streaming fragment data: %s", err)
  	}
  }
docs: // handleGetFragmentData handles GET /internal/fragment/data requests.