def add_node(self, klass):
        name = klass.__name__
        if not self.nodes.has_key(name):
            node = TreeNode(klass)
            self.nodes[name] = node
            return node
Create a node for the given class.
dataset/ETHPy150Open VisTrails/VisTrails/contrib/titan/class_tree.py/ClassTree.add_node