code: func (h *Handler) handleGetVersion(w http.ResponseWriter, r *http.Request) {
  	if !validHeaderAcceptJSON(r.Header) {
  		http.Error(w, "JSON only acceptable response", http.StatusNotAcceptable)
  		return
  	}
  	err := json.NewEncoder(w).Encode(struct {
  		Version string `json:"version"`
  	}{
  		Version: h.api.Version(),
  	})
  	if err != nil {
  		h.logger.Printf("write version response error: %s", err)
  	}
  }
docs: // handleGetVersion handles /version requests.