code: func (api UsersAPI) CreateAvatarFromLink(w http.ResponseWriter, r *http.Request) {
  	username := mux.Vars(r)["username"]
  
  	avatar := user.Avatar{}
  
  	if err := json.NewDecoder(r.Body).Decode(&avatar); err != nil {
  		http.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
  		return
  	}
  
  	userMgr := user.NewManager(r)
  	u, err := userMgr.GetByName(username)
  	if handleServerError(w, "getting user by name", err) {
  		return
  	}
  
  	if !validateNewAvatar(w, avatar.Label, u) {
  		return
  	}
  
  	userMgr.SaveAvatar(username, avatar)
  
  	w.WriteHeader(http.StatusCreated)
  	json.NewEncoder(w).Encode(&avatar)
  }
docs: // CreateAvatarFromLink is the handler for POST /users/{username}/avatar/link
  // create a new avatar with the specified label