public static class NotificationExtensions
    {
        /// <summary>
        /// Subscribe to PropertyChange notifications for the  given property.
        /// </summary>
        /// <param name="notifier">
        /// Implementer of <see cref="INotifyPropertyChanged"/> that the events are going to be coming from.
        /// </param>
        /// <param name="propertyExpression">
        /// Lambda expression pointing to the property that you want to receive change notifications for.
        /// </param>
        /// <param name="handler">
        /// Event handler of the PropertyChange notifications.
        /// </param>
        public static void SubscribeToChanges<T>(
            this T notifier,
            Expression<Func<T, object>> propertyExpression,
            PropertyChangedEventHandler handler) 
            where T : INotifyPropertyChanged
        {
            MemberExpression memberExpression;
            var unaryExpression = propertyExpression.Body as UnaryExpression;
            if (unaryExpression != null)
            {
                memberExpression = (MemberExpression)unaryExpression.Operand;
            }
            else
            {
                memberExpression = (MemberExpression)propertyExpression.Body;
            }
            var propertyInfo = (PropertyInfo)memberExpression.Member;

            string propertyName = propertyInfo.Name;

            notifier.PropertyChanged += (s, e) =>
            {
                if (e.PropertyName.Equals(propertyName) || string.IsNullOrEmpty(e.PropertyName))
                {
                    handler(s, e);
                }
            };
        }
    }