public static ISyntaxNodeViewModel Ancestor <T>(this ISyntaxNodeViewModel @this)
        {
            Type ancestorType             = typeof(T);
            ISyntaxNodeViewModel ancestor = @this.Owner;

            while (ancestor != null)
            {
                if (ancestor.GetType() != ancestorType)
                {
                    ancestor = ancestor.Owner;
                }
                else
                {
                    break;
                }
            }
            return(ancestor);
        }