anchor.diff:      if (to.tryAdd(item)) {
         from.removeAt(index);
       } else {
  -      // TODO(bob): Show an error message?
  +      // TODO: Show an error message?
       }
   
       if (home.rightView == HomeView.CRUCIBLE) home.refreshRecipe();
  
positive.code: /// What the user is currently doing on the home screen.
  abstract class HomeMode {
    static final VIEW = const ViewHomeMode();
    static final DROP = const DropHomeMode();
    static final GET = const GetHomeMode();
  
    const HomeMode();
  
negative.code: 
      if (to.tryAdd(item)) {
        from.removeAt(index);
  
        // If we get the last item, automatically switch out of get mode.
        if (from.isEmpty) home.mode = HomeMode.VIEW;
      } else {
        // TODO: Show an error message?
      }
  
      if (home.rightView == HomeView.CRUCIBLE) home.refreshRecipe();
  