public EvaluationTreeTestViewModel()
{
var node1 = new ComparisonOperator <string>("a", "b", BooleanOperatorTypeEnum.EqualOrLess);
var node2 = new ComparisonOperator <string>("c", "d", BooleanOperatorTypeEnum.EqualOrGreater);
var node3 = new AndOperator(node1, node2);
Debug.WriteLine(string.Format("{0} = {1}", node1.GetNodeAsString(), node1.GetResult()));
Debug.WriteLine(string.Format("{0} = {1}", node2.GetNodeAsString(), node2.GetResult()));
Debug.WriteLine(string.Format("{0} = {1}", node3.GetNodeAsString(), node3.GetResult()));
}