/// <summary>
        /// Negates the invocation expression.
        /// </summary>
        /// <param name="factory">
        /// The factory.
        /// </param>
        /// <param name="invocationExpression">
        /// The invocation expression.
        /// </param>
        private static void NegateInvocationExpression(CSharpElementFactory factory, IInvocationExpression invocationExpression)
        {
            var expression = factory.CreateExpression("!" + invocationExpression.GetText());

              invocationExpression.ReplaceBy(expression);
        }