Job for List of classes which extends salesformletter

Job for List of classes which extends salesformletter:-
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static void listofclasses_salesformletter(Args _args)
{
    treeNode childNode;
    treenodeIterator it;
    str properties;
    str className;
    str extend;
    str searchType = "Salesformletter";
    int x;
    treeNode t  = TreeNode::findNode('\\Classes');
    ;

    it = t.AOTiterator();
    childNode= it.next();
    while (childNode)
    {
        className = childNode.treeNodeName();
        properties = childNode.AOTgetProperties();
        extend = findProperty(properties, "Extends");

        if (extend == searchType)
        {
            info(strfmt("%1 – ExtendedDataType: %2", className,extend));
        }

        childNode= it.next();
    }