public static CompletionExpressionCounter On(ISST sst)
        {
            var counter = new CompletionExpressionCounter();

            sst.Accept(new HasCompletionExpressionVisitor(), counter);
            return(counter);
        }
 public override void Visit(ICompletionExpression expr, CompletionExpressionCounter context)
 {
     context.Add();
 }