anchor.diff:  import 'dart:html';
   
   import 'package:angular/angular.dart';
  +import 'package:angular_forms/angular_forms.dart';
   import 'package:meta/meta.dart';
   import 'package:angular_components/interfaces/has_disabled.dart';
   import 'package:angular_components/utils/browser/events/events.dart';
  
positive.code:     if (!disabled) {
        checked = !checked;
        _controller.add(checked);
      }
    }
  
  
negative.code:     if (toggleElement == null) return;
      toggleElement.attributes['aria-pressed'] = '$checked';
    }
  
    @override
    void writeValue(bool isChecked) {
      checked = isChecked;
      _changeDetector?.markForCheck();
    }
  
    @override
    void registerOnChange(ChangeFunction<bool> callback) {
      onChecked.listen((checked) => callback(checked));
    }
  
    @override
    void registerOnTouched(TouchFunction callback) {
      _onTouched = callback;
    }
  
    @override
    void onDisabledChanged(bool isDisabled) {
      disabled = isDisabled;
      _changeDetector?.markForCheck();
    }
  }
  