private static void GetNodesFromLevelHelper(SortedTree <ClassAsTreeValue <string> > tree, string expected, int level)
{
string actual = "";
foreach (SortedTree <ClassAsTreeValue <string> > .SortedTreeNode value in tree.GetNodesFromLevel(level))
{
actual += value.Value.ToString();
}
Assert.AreEqual(expected, actual, "Problem with GetNodesFromLevel level:" + level.ToString());
}