code: func valueDescriptorByIdHandler(w http.ResponseWriter, r *http.Request) {
  	defer r.Body.Close()
  
  	vars := mux.Vars(r)
  	id := vars["id"]
  
  	switch r.Method {
  	case http.MethodGet:
  		vd, err := getValueDescriptorById(id)
  		if err != nil {
  			switch err.(type) {
  			case *errors.ErrDbNotFound:
  				http.Error(w, err.Error(), http.StatusNotFound)
  				return
  			default:
  				http.Error(w, err.Error(), http.StatusInternalServerError)
  				return
  			}
  		}
  
  		encode(vd, w)
  	}
  }
docs: // Get a value descriptor based on the ID
  // HTTP 404 not found if the ID isn't in the database
  // api/v1/valuedescriptor/{id}